Method and apparatus for transmitting and receiving signals by side link terminal in wireless communication system

ABSTRACT

One embodiment relates to a method for receiving a signal by a second base station in a wireless communication system, comprising: a step in which the second base station receives a second signal that a terminal which received a first signal from a first base station transmits after a first interval; a step in which the second base station receives a fourth signal that a terminal which received a third signal from the second base station transmits after the first interval, wherein a synchronization error between the first base station and the second base station is determined on the basis of a point in time when the second base station receives the second signal and a point in time when the second base station receives the fourth signal.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly to a method for adjusting synchronization between basestations and a method and apparatus for performing ellipsoid-basedpositioning.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services such as voice or data. Ingeneral, the wireless communication systems are multiple access systemscapable of supporting communication between multiple users by sharingavailable system resources (e.g., bandwidth, transmit power, etc.). Themultiple access systems include, for example, a code division multipleaccess (CDMA) system, a frequency division multiple access (FDMA)system, a time division multiple access (TDMA) system, an orthogonalfrequency division multiple access (OFDMA) system, a single carrierfrequency division multiple access (SC-FDMA) system, and a multi-carrierfrequency division multiple access (MC-FDMA) system.

In a wireless communication system, a variety of radio accesstechnologies (RATs) such as LTE, LTE-A, and Wi-Fi are used and the fifthgeneration of wireless technology (5G) belongs to the RATs. Three mainrequirement categories for 5G include (1) a category of enhanced mobilebroadband (eMBB), (2) a category of massive machine type communication(mMTC), and (3) a category of ultra-reliable and low-latencycommunications (URLLC). Partial use cases may require a plurality ofcategories for optimization and other use cases may focus upon only onekey performance indicator (KPI). 5G supports such various use casesusing a flexible and reliable method.

eMBB far surpasses basic mobile Internet access and covers abundantbidirectional work and media and entertainment applications in cloud andaugmented reality. Data is one of a core driving force of 5G and, in the5G era, a dedicated voice service may not be provided for the firsttime. In 5G, it is expected that voice will simply be processed as anapplication program using data connection provided by a communicationsystem. Main causes for increased traffic volume are increase in thesize of content and an increase in the number of applications requiringhigh data transmission rate. A streaming service (of audio and video),conversational video, and mobile Internet access will be more widelyused as more devices are connected to the Internet. These applicationprograms require always-on connectivity in order to push real-timeinformation and alerts to users. Cloud storage and applications arerapidly increasing in a mobile communication platform and may be appliedto both work and entertainment. Cloud storage is a special use casewhich accelerates growth of uplink data transmission rate. 5G is alsoused for cloud-based remote work. When a tactile interface is used, 5Gdemands much lower end-to-end latency to maintain good user experience.Entertainment, for example, cloud gaming and video streaming, is anothercore element which increases demand for mobile broadband capability.Entertainment is essential for a smartphone and a tablet in any placeincluding high mobility environments such as a train, a vehicle, and anairplane. Other use cases are augmented reality for entertainment andinformation search. In this case, the augmented reality requires verylow latency and instantaneous data volume.

In addition, one of the most expected 5G use cases relates to a functioncapable of smoothly connecting embedded sensors in all fields, i.e.,mMTC. It is expected that the number of potential IoT devices will reach20.4 billion up to the year of 2020. Industrial IoT is one of categoriesof performing a main role enabling a smart city, asset tracking, smartutilities, agriculture, and security infrastructure through 5G.

URLLC includes new services that will transform industries withultra-reliable/available, low-latency links such as remote control ofcritical infrastructure and a self-driving vehicle. A level ofreliability and latency is essential to control and adjust a smart grid,industrial automation, robotics, and a drone.

Next, a plurality of use cases will be described in more detail.

5G is a means of providing streaming at a few hundred megabits persecond to gigabits per second and may complement fiber-to-the-home(FTTH) and cable-based broadband (or DOCSIS). Such high speed is neededto deliver TV at a resolution of 4K or more (6K, 8K, and more), as wellas virtual reality and augmented reality. Virtual reality (VR) andaugmented reality (AR) applications include immersive sports games. Aspecific application program may require a special networkconfiguration. For example, for VR games, gaming companies need toincorporate a core server into an edge network server of a networkoperator in order to minimize latency.

Automotive is expected to be a new important driving force in 5Gtogether with many use cases for mobile communication for vehicles. Forexample, entertainment for passengers requires high simultaneouscapacity and mobile broadband with high mobility. This is because futureusers continue to expect high connection quality regardless of locationand speed. Another automotive use case is an AR dashboard. The ARdashboard displays information talking to a driver about a distance toan object and movement of the object by being superimposed on an objectseen from a front window to identify an object in the dark. In thefuture, a wireless module will enable communication between vehicles,information exchange between a vehicle and supporting infrastructure,and information exchange between a vehicle and other connected devices(e.g., devices transported by a pedestrian). A safety system guidesalternative courses of a behavior so that a driver may drive more safelydrive, thereby lowering the danger of an accident. The next stage willbe a remotely controlled or self-driven vehicle. This requires very highreliability and very fast communication between different self-drivenvehicles and between a vehicle and infrastructure. In the future, aself-driven vehicle will perform all driving activities and a driverwill focus only upon abnormal traffic that the vehicle cannot identify.Technical requirements of a self-driven vehicle demand ultra-low latencyand ultra-high reliability so that traffic safety is increased to alevel that cannot be achieved by a human being.

A smart city and a smart home mentioned as a smart society will beembedded in a high-density wireless sensor network. A distributednetwork of an intelligent sensor will identify conditions for costs andenergy-efficient maintenance of a city or a home. Similar configurationsmay be performed for respective households. All temperature sensors,window and heating controllers, burglar alarms, and home appliances arewirelessly connected. Many of these sensors are typically low in datatransmission rate, power, and cost. However, real-time HD video may bedemanded by a specific type of device to perform monitoring.

Consumption and distribution of energy including heat or gas is highlydecentralized so that automated control of the distribution sensornetwork is demanded. The smart grid collects information and connectsthe sensors to each other using digital information and communicationtechnology so as to act according to the collected information. Sincethis information may include behaviors of a supply company and aconsumer, the smart grid may improve distribution of energy such aselectricity by a method having efficiency, reliability, economicfeasibility, sustainability of production, and automatability. The smartgrid may also be regarded as another sensor network having low latency.

A health care part contains many application programs capable ofenjoying the benefits of mobile communication. A communication systemmay support remote treatment that provides clinical treatment in afaraway place. Remote treatment may aid in reducing a barrier againstdistance and improve access to medical services that cannot becontinuously available in a faraway rural area. Remote treatment is alsoused to perform important treatment and save lives in an emergencysituation. The wireless sensor network based on mobile communication mayprovide remote monitoring and sensors for parameters such as heart rateand blood pressure.

Wireless and mobile communication gradually becomes important in anindustrial application field. Wiring is high in installation andmaintenance cost. Therefore, a possibility of replacing a cable withreconstructible wireless links is an attractive opportunity in manyindustrial fields. However, in order to achieve this replacement, it isnecessary for wireless connection to be established with latency,reliability, and capacity similar to those of cables and management ofwireless connection needs to be simplified. Low latency and a very lowerror probability are new requirements when connection to 5G is needed.

Logistics and freight tracking are important use cases for mobilecommunication that enables inventory and package tracking anywhere usinga location-based information system. The use cases of logistics andfreight tracking typically demand low data rate but require locationinformation with a wide range and reliability.

DISCLOSURE Technical Problem

An object of the present disclosure is to provide a method for adjustingsynchronization between base stations and an ellipsoid-based positioningmethod.

Objects that are intend to be achieved with embodiment(s) are notlimited to what has been particularly described hereinabove and otherobjects not described herein will be more clearly understood by personsskilled in the art to which embodiment(s) pertain from the followingdescription.

Technical Solutions

In accordance with one aspect of the present disclosure, a method forreceiving signals by a second base station (BS) in a wirelesscommunication system may include receiving, by the second base station(BS), a second signal transmitted after lapse of a first interval by auser equipment (UE) having received a first signal from a first basestation (BS); and receiving, by the second base station (BS), a fourthsignal transmitted after lapse of the first interval by the userequipment (UE) having received a third signal from a second base station(BS), wherein a synchronization error between the first base station(BS) and the second base station (BS) is determined based on a timepoint where the second base station (BS) receives the second signal anda time point where the second base station (BS) receives the fourthsignal.

In accordance with another aspect of the present disclosure, a secondbase station for use in a wireless communication system may include amemory and a plurality of processors coupled to the memory. At least oneprocessor from among the plurality of processors may receive a secondsignal transmitted after lapse of a first interval by a user equipment(UE) having received a first signal from a first base station (BS), andmay receive a fourth signal transmitted after lapse of the firstinterval by the user equipment (UE) having received a third signal froma second base station (BS). A synchronization error between the firstbase station (BS) and the second base station (BS) may be determinedbased on a time point where the second base station (BS) receives thesecond signal and a time point where the second base station (BS)receives the fourth signal.

The second base station (BS) may be synchronized with the first basestation (BS) based on the synchronization error.

The second base station (BS) may be configured to measure a position ofthe user equipment (UE) based on an elliptical shape derived from areception time of a sixth signal transmitted after lapse of a secondinterval by the user equipment (UE) having received a fifth signal fromthe first base station (BS).

The first signal and the third signal may be transmitted at the sametime by the first base station (BS) and the second base station (BS)having the synchronization error.

The synchronization error may be determined from a proposition that eachof the first interval, a distance between the user equipment (UE) andthe first base station (BS), a distance between the UE and the secondbase station (BS), a time difference between a time point where thesecond base station (BS) receives the second signal and a time pointwhere the second base station (BS) receives the fourth signal isidentical to a time difference between a time point where the userequipment (UE) receives the first signal and a time point where the userequipment (UE) receives the third signal.

The distance between the user equipment (UE) and the second base station(BS) may be calculated based on the first interval and a time durationfrom a transmission time of the third signal to a reception time of thefourth signal after transmission of the third signal.

The distance between the user equipment (UE) and the first base station(BS) may be received from the first base station (BS).

The distance between the user equipment (UE) and the first base station(BS) may be calculated based on the first interval and a time durationfrom a transmission time point where the first base station (BS)transmits the first signal to a reception time point where the firstbase station (BS) receives the second signal.

The first interval may be received from the user equipment (UE).

A time difference between a time point where the user equipment (UE)receives the first signal and a time point where the user equipment (UE)receives the third signal may be received from the user equipment (UE).

The proposition is represented by a following equation:

$\begin{matrix}{{t_{0} + {e\left( {a,b} \right)} + t_{{Rx} - {Tx}} + \frac{d_{b,{UE}}}{c} + \frac{d_{a,{UE}}}{c}} = {t_{0} + \frac{2d_{a,{UE}}}{c} + {{RSTD}\left( {a,b} \right)} + t_{{Rx} - {Tx}}}} & \lbrack{Equation}\rbrack\end{matrix}$

where, t⁰ denotes the same time point e(a,b) denotes the synchronizationerror, t_(Rx-Tx) denotes the first interval, d_(a,UE) denotes thedistance between the UE and the first BS, d_(b,UE) denotes the distancebetween the UE and the second BS, and RSTD(a,b) denotes a timedifference between a time point where the user equipment (UE) receivesthe first signal and a time point where the user equipment (UE) receivesthe third signal.

The user equipment (UE) may be an autonomous driving vehicle or may beembedded in the autonomous driving vehicle.

Advantageous Effects

The present disclosure can search for a complex intersection in relationto ToA-, OTDoA-, UTDoA-based positioning and the proposedellipsoid-based positioning, and can more precisely perform positioning.As a result, the present disclosure can effectively estimate thesynchronization error between anchor nodes.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of embodiment(s), illustrate various embodiments andtogether with the description of the specification serve to explain theprinciple of the specification.

FIG. 1 is a diagram illustrating a vehicle according to embodiment(s).

FIG. 2 is a control block diagram of the vehicle according toembodiment(s).

FIG. 3 is a control block diagram of an autonomous device according toembodiment(s).

FIG. 4 is a block diagram of the autonomous device according toembodiment(s).

FIG. 5 is a diagram showing the interior of the vehicle according toembodiment(s).

FIG. 6 is a block diagram referred to in description of a cabin systemfor the vehicle according to embodiment(s).

FIG. 7 illustrates the structure of an LTE system to which embodiment(s)are applicable.

FIG. 8 illustrates a radio protocol architecture for a user plane towhich embodiment(s) are applicable.

FIG. 9 illustrates a radio protocol architecture for a control plane towhich embodiment(s) are applicable.

FIG. 10 illustrates the structure of an NR system to which embodiment(s)are applicable.

FIG. 11 illustrates functional split between an NG-RAN and a 5GC towhich embodiment(s) are applicable.

FIG. 12 illustrates the structure of an NR radio frame to whichembodiment(s) are applicable.

FIG. 13 illustrates the structure of a slot of an NR frame to whichembodiment(s) are applicable.

FIG. 14 illustrates an example of selecting a transmission resource towhich embodiments(s) are applicable.

FIG. 15 illustrates an example of transmitting a PSCCH in sidelinktransmission mode 3 or 4 to which embodiment(s) are applicable.

FIG. 16 illustrates an example of physical processing at a transmittingside to which embodiment(s) are applicable.

FIG. 17 illustrates an example of physical layer processing at areceiving side to which embodiment(s) are applicable.

FIG. 18 illustrates a synchronization source or synchronizationreference in V2X to which embodiment(s) are applicable.

FIG. 19 illustrates an SS/PBCH block to which embodiment(s) areapplicable.

FIG. 20 illustrates a method of acquiring timing information by a UE.

FIG. 21 is a diagram referred to in description of a procedure ofacquiring system information to which embodiment(s) are applicable.

FIG. 22 is a diagram referred to in description of a random accessprocedure to which embodiment(s) are applicable.

FIG. 23 is a diagram referred to in description of a threshold of an SSblock to which embodiment(s) are applicable.

FIG. 24 is a diagram referred to in description of beam switching forPRACH retransmission to which embodiment(s) are applicable.

FIGS. 25 and 26 illustrate parity-check matrices to which embodiment(s)are applicable.

FIG. 27 illustrates an encoder structure for a polar code to whichembodiment(s) are applicable.

FIG. 28 illustrates channel combining and channel splitting to whichembodiment(s) are applicable.

FIG. 29 illustrates UE RRC state transition to which embodiment(s) areapplicable.

FIG. 30 illustrates state transition between an NR/NGC and anE-UTRAN/EPC to which embodiment(s) are applicable.

FIG. 31 illustrates a DRX cycle to which embodiment(s) are applicable.

FIG. 32 is a flowchart illustrating embodiment(s) of the presentdisclosure.

FIGS. 33 to 36 are diagrams illustrating the embodiment(s) of thepresent disclosure.

FIGS. 37 to 43 are diagrams illustrating various devices to which theembodiment(s) can be applied.

BEST MODE

1. Driving

(1) Exterior of Vehicle

FIG. 1 is a diagram illustrating a vehicle according to embodiment(s).

Referring to FIG. 1, a vehicle 10 according to embodiment(s) is definedas a transportation means traveling on roads or railroads. The vehicle10 includes a car, a train, and a motorcycle. The vehicle 10 may includean internal combustion engine vehicle having an engine as a powersource, a hybrid vehicle having an engine and a motor as a power source,and an electric vehicle having an electric motor as a power source. Thevehicle 10 may be a privately owned vehicle. The vehicle 10 may be ashared vehicle. The vehicle 10 may be an autonomous driving vehicle.

(2) Components of Vehicle

FIG. 2 is a control block diagram of the vehicle according toembodiment(s).

Referring to FIG. 2, the vehicle 10 may include a user interface device200, an object detection device 210, a communication device 220, adriving operation device 230, a main electronic control unit (ECU) 240,a driving control device 250, an autonomous driving device 260, asensing unit 270, and a position data generation device 280. The objectdetection device 210, the communication device 220, the drivingoperation device 230, the main ECU 240, the driving control device 250,the autonomous driving device 260, the sensing unit 270 and the positiondata generation device 280 may be implemented by electronic deviceswhich generate electric signals and exchange the electric signals withone another.

1) User Interface Device

The user interface device 200 is a device for communication between thevehicle 10 and a user. The user interface device 200 may receive userinput and provide information generated in the vehicle 10 to the user.The vehicle 10 may implement a user interface (UI) or user experience(UX) through the user interface device 200. The user interface device200 may include an input device, an output device, and a user monitoringdevice.

2) Object Detection Device

The object detection device 210 may generate information about objectsoutside the vehicle 10. Information about an object may include at leastone of information about presence or absence of the object, informationabout the position of the object, information about a distance betweenthe vehicle 10 and the object, or information about a relative speed ofthe vehicle 10 with respect to the object. The object detection device210 may detect objects outside the vehicle 10. The object detectiondevice 210 may include at least one sensor which may detect objectsoutside the vehicle 10. The object detection device 210 may include atleast one of a camera, a radar, a lidar, an ultrasonic sensor, or aninfrared sensor. The object detection device 210 may provide data aboutan object generated based on a sensing signal generated from a sensor toat least one electronic device included in the vehicle.

2.1) Camera

The camera may generate information about objects outside the vehicle 10using images. The camera may include at least one lens, at least oneimage sensor, and at least one processor which is electrically connectedto the image sensor, processes received signals, and generates dataabout objects based on the processed signals.

The camera may be at least one of a mono camera, a stereoscopic camera,or an around view monitoring (AVM) camera. The camera may acquireinformation about the position of an object, information about adistance to the object, or information about a relative speed withrespect to the object using various image processing algorithms. Forexample, the camera may acquire information about a distance to anobject and information about a relative speed with respect to the objectfrom an acquired image based on change in the size of the object overtime. For example, the camera may acquire information about a distanceto an object and information about a relative speed with respect to theobject through a pin-hole model, road profiling, or the like. Forexample, the camera may acquire information about a distance to anobject and information about a relative speed with respect to the objectfrom a stereoscopic image acquired from a stereoscopic camera based ondisparity information.

The camera may be mounted in a portion of the vehicle at which field ofview (FOV) may be secured in order to capture the outside of thevehicle. The camera may be disposed in proximity to a front windshieldinside the vehicle in order to acquire front view images of the vehicle.The camera may be disposed near a front bumper or a radiator grill. Thecamera may be disposed in proximity to a rear glass inside the vehiclein order to acquire rear view images of the vehicle. The camera may bedisposed near a rear bumper, a trunk, or a tail gate. The camera may bedisposed in proximity to at least one of side windows inside the vehiclein order to acquire side view images of the vehicle. Alternatively, thecamera may be disposed near a side mirror, a fender, or a door.

2.2) Radar

The radar may generate information about an object outside the vehicle10 using electromagnetic waves. The radar may include an electromagneticwave transmitter, an electromagnetic wave receiver, and at least oneprocessor which is electrically connected to the electromagnetic wavetransmitter and the electromagnetic wave receiver, processes receivedsignals, and generates data about an object based on the processedsignals. The radar may be implemented as a pulse radar or a continuouswave radar in terms of electromagnetic wave emission. The continuouswave radar may be implemented as a frequency modulated continuous wave(FMCW) radar or a frequency shift keying (FSK) radar according to signalwaveform. The radar may detect an object through electromagnetic wavesbased on time of flight (TOF) or phase shift and detect the position ofthe detected object, a distance to the detected object, and a relativespeed with respect to the detected object. The radar may be disposed atan appropriate position outside the vehicle in order to detect objectspositioned in front of, behind, or on the side of the vehicle.

2.3) Lidar

The lidar may generate information about an object outside the vehicle10 using a laser beam. The lidar may include a light transmitter, alight receiver, and at least one processor which is electricallyconnected to the light transmitter and the light receiver, processesreceived signals, and generates data about an object based on theprocessed signals. The lidar may be implemented as a TOF type or a phaseshift type. The lidar may be implemented as a driven type or anon-driven type. A driven type lidar may be rotated by a motor anddetect an object around the vehicle 10. A non-driven type lidar maydetect an object positioned within a predetermined range from thevehicle according to light steering. The vehicle 10 may include aplurality of non-driven type lidars. The lidar may detect an objectthrough a laser beam based on the TOF type or the phase shift type anddetect the position of the detected object, a distance to the detectedobject, and a relative speed with respect to the detected object. Thelidar may be disposed at an appropriate position outside the vehicle inorder to detect objects positioned in front of, behind, or on the sideof the vehicle.

3) Communication Device

The communication device 220 may exchange signals with devices disposedoutside the vehicle 10. The communication device 220 may exchangesignals with at least one of infrastructure (e.g., a server and abroadcast station), another vehicle, or a terminal. The communicationdevice 220 may include at least one of a transmission antenna, areception antenna, or a radio frequency (RF) circuit or an RF elementwhich may implement various communication protocols, in order to performcommunication.

For example, the communication device may exchange signals with externaldevices based on cellular V2X (C-V2X). For example, C-V2X may includeside-link communication based on LTE and/or side-link communicationbased on NR. Details related to C-V2X will be described later.

For example, the communication device may exchange signals with externaldevices based on dedicated short range communications (DSRC) or wirelessaccess in vehicular environment (WAVE) based on IEEE 802.11p physical(PHY)/media access control (MAC layer technology and IEEE 1609network/transport layer technology. DSRC (or WAVE) is communicationspecification for providing an intelligent transport system (ITS)service through short-range dedicated communication betweenvehicle-mounted devices or between a roadside device and avehicle-mounted device. DSRC may be a communication scheme that may usea frequency of 5.9 GHz and have a data transmission rate in the range of3 Mbps to 27 Mbps. IEEE 802.11p may be combined with IEEE 1609 tosupport DSRC (or WAVE).

The communication device of embodiment(s) may exchange signals withexternal devices using only one of C-V2X and DSRC. Alternatively, thecommunication device of embodiment(s) may exchange signals with externaldevices using a hybrid of C-V2X and DSRC.

4) Driving Operation Device

The driving operation device 230 is a device for receiving user inputfor driving. In a manual mode, the vehicle 10 may be driven based on asignal provided by the driving operation device 230. The drivingoperation device 230 may include a steering input device (e.g., asteering wheel), an acceleration input device (e.g., an acceleratorpedal), and a brake input device (e.g., a brake pedal).

5) Main ECU

The main ECU 240 may control the overall operation of at least oneelectronic device included in the vehicle 10.

6) Driving Control Device

The driving control device 250 is a device for electrically controllingvarious vehicle driving devices included in the vehicle 10. The drivingcontrol device 250 may include a powertrain driving control device, achassis driving control device, a door/window driving control device, asafety device driving control device, a lamp driving control device, andan air-conditioner driving control device. The powertrain drivingcontrol device may include a power source driving control device and atransmission driving control device. The chassis driving control devicemay include a steering driving control device, a brake driving controldevice, and a suspension driving control device. Meanwhile, the safetydevice driving control device may include a seat belt driving controldevice for seat belt control.

The driving control device 250 includes at least one electronic controldevice (e.g., an ECU).

The driving control device 250 may control vehicle driving devices basedon signals received by the autonomous device 260. For example, thedriving control device 250 may control a powertrain, a steering device,and a brake device based on signals received by the autonomous device260.

7) Autonomous Driving Device

The autonomous driving device 260 may generate a route for self-drivingbased on acquired data. The autonomous driving device 260 may generate adriving plan for traveling along the generated route. The autonomousdriving device 260 may generate a signal for controlling movement of thevehicle according to the driving plan. The autonomous device 260 mayprovide the generated signal to the driving control device 250.

The autonomous driving device 260 may implement at least one advanceddriver assistance system (ADAS) function. The ADAS may implement atleast one of adaptive cruise control (ACC), autonomous emergency braking(AEB), forward collision warning (FCW), lane keeping assist (LKA), lanechange assist (LCA), target following assist (TFA), blind spot detection(BSD), adaptive high beam assist (HBA), automated parking system (APS),a pedestrian collision warning system, traffic sign recognition (TSR),traffic sign assist (TSA), night vision (NV), driver status monitoring(DSM), or traffic jam assist (TJA).

The autonomous driving device 260 may perform switching from aself-driving mode to a manual driving mode or switching from the manualdriving mode to the self-driving mode. For example, the autonomousdriving device 260 may switch the mode of the vehicle 10 from theself-driving mode to the manual driving mode or from the manual drivingmode to the self-driving mode, based on a signal received from the userinterface device 200.

8) Sensing Unit

The sensing unit 270 may detect a state of the vehicle. The sensing unit270 may include at least one of an internal measurement unit (IMU)sensor, a collision sensor, a wheel sensor, a speed sensor, aninclination sensor, a weight sensor, a heading sensor, a positionmodule, a vehicle forward/backward movement sensor, a battery sensor, afuel sensor, a tire sensor, a steering sensor, a temperature sensor, ahumidity sensor, an ultrasonic sensor, an illumination sensor, or apedal position sensor. Further, the IMU sensor may include one or moreof an acceleration sensor, a gyro sensor, and a magnetic sensor.

The sensing unit 270 may generate vehicle state data based on a signalgenerated from at least one sensor. The vehicle state data may beinformation generated based on data detected by various sensors includedin the vehicle. The sensing unit 270 may generate vehicle attitude data,vehicle motion data, vehicle yaw data, vehicle roll data, vehicle pitchdata, vehicle collision data, vehicle orientation data, vehicle angledata, vehicle speed data, vehicle acceleration data, vehicle tilt data,vehicle forward/backward movement data, vehicle weight data, batterydata, fuel data, tire pressure data, vehicle internal temperature data,vehicle internal humidity data, steering wheel rotation angle data,vehicle external illumination data, data of a pressure applied to anacceleration pedal, data of a pressure applied to a brake pedal, etc.

9) Position Data Generation Device

The position data generation device 280 may generate position data ofthe vehicle 10. The position data generation device 280 may include atleast one of a global positioning system (GPS) or a differential globalpositioning system (DGPS). The position data generation device 280 maygenerate position data of the vehicle 10 based on a signal generatedfrom at least one of the GPS or the DGPS. According to an embodiment,the position data generation device 280 may correct position data basedon at least one of the IMU sensor of the sensing unit 270 or the cameraof the object detection device 210. The position data generation device280 may also be called a global navigation satellite system (GNSS).

The vehicle 10 may include an internal communication system 50. Aplurality of electronic devices included in the vehicle 10 may exchangesignals through the internal communication system 50. The signals mayinclude data. The internal communication system 50 may use at least onecommunication protocol (e.g., CAN, LIN, FlexRay, MOST or Ethernet).

(3) Components of Autonomous Driving Device

FIG. 3 is a control block diagram of the autonomous driving deviceaccording to embodiment(s).

Referring to FIG. 3, the autonomous driving device 260 may include amemory 140, a processor 170, an interface 180, and a power supply 190.

The memory 140 is electrically connected to the processor 170. Thememory 140 may store basic data with respect to units, control data foroperation control of units, and input/output data. The memory 140 maystore data processed in the processor 170. Hardware-wise, the memory 140may be configured as at least one of a ROM, a RAM, an EPROM, a flashdrive, or a hard drive. The memory 140 may store various types of datafor overall operation of the autonomous driving device 260, such as aprogram for processing or control of the processor 170. The memory 140may be integrated with the processor 170. According to an embodiment,the memory 140 may be categorized as a subcomponent of the processor170.

The interface 180 may exchange signals with at least one electronicdevice included in the vehicle 10 by wire or wirelessly. The interface180 may exchange signals with at least one of the object detectiondevice 210, the communication device 220, the driving operation device230, the main ECU 240, the driving control device 250, the sensing unit270, or the position data generation device 280 in a wired or wirelessmanner. The interface 180 may be configured using at least one of acommunication module, a terminal, a pin, a cable, a port, a circuit, anelement, or a device.

The power supply 190 may provide power to the autonomous driving device260. The power supply 190 may be provided with power from a power source(e.g., a battery) included in the vehicle 10 and supply the power toeach unit of the autonomous driving device 260. The power supply 190 mayoperate according to a control signal supplied from the main ECU 240.The power supply 190 may include a switched-mode power supply (SMPS).

The processor 170 may be electrically connected to the memory 140, theinterface 180, and the power supply 190 and exchange signals with thesecomponents. The processor 170 may be implemented using at least one ofapplication specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, microcontrollers, microprocessors, orelectronic units for executing other functions.

The processor 170 may be operated by power supplied from the powersupply 190. The processor 170 may receive data, process the data,generate a signal, and provide the signal while power is being suppliedthereto.

The processor 170 may receive information from other electronic devicesincluded in the vehicle 10 through the interface 180. The processor 170may provide control signals to other electronic devices in the vehicle10 through the interface 180.

The autonomous driving device 260 may include at least one printedcircuit board (PCB). The memory 140, the interface 180, the power supply190, and the processor 170 may be electrically connected to the PCB.

(4) Operation of Autonomous Driving Device

1) Reception Operation

Referring to FIG. 4, the processor 170 may perform a receptionoperation. The processor 170 may receive data from at least one of theobject detection device 210, the communication device 220, the sensingunit 270, or the position data generation device 280 through theinterface 180. The processor 170 may receive object data from the objectdetection device 210. The processor 170 may receive HD map data from thecommunication device 220. The processor 170 may receive vehicle statedata from the sensing unit 270. The processor 170 may receive positiondata from the position data generation device 280.

2) Processing/Determination Operation

The processor 170 may perform a processing/determination operation. Theprocessor 170 may perform the processing/determination operation basedon traveling situation information. The processor 170 may perform theprocessing/determination operation based on at least one of the objectdata, the HD map data, the vehicle state data, or the position data.

2.1) Driving Plan Data Generation Operation

The processor 170 may generate driving plan data. For example, theprocessor 170 may generate electronic horizon data. The electronichorizon data may be understood as driving plan data in a range from aposition at which the vehicle 10 is located to a horizon. The horizonmay be understood as a point a predetermined distance before theposition at which the vehicle 10 is located based on a predeterminedtraveling route. The horizon may refer to a point at which the vehiclemay arrive after a predetermined time from the position at which thevehicle 10 is located along a predetermined traveling route.

The electronic horizon data may include horizon map data and horizonpath data.

2.1.1) Horizon Map Data

The horizon map data may include at least one of topology data, roaddata, HD map data, or dynamic data. According to an embodiment, thehorizon map data may include a plurality of layers. For example, thehorizon map data may include a first layer that matches the topologydata, a second layer that matches the road data, a third layer thatmatches the HD map data, and a fourth layer that matches the dynamicdata. The horizon map data may further include static object data.

The topology data may be explained as a map created by connecting roadcenters. The topology data is suitable for approximate display of alocation of a vehicle and may have a data form used for navigation fordrivers. The topology data may be understood as data about roadinformation other than information on driveways. The topology data maybe generated based on data received from an external server through thecommunication device 220. The topology data may be based on data storedin at least one memory included in the vehicle 10.

The road data may include at least one of road slope data, roadcurvature data, or road speed limit data. The road data may furtherinclude no-passing zone data. The road data may be based on datareceived from an external server through the communication device 220.The road data may be based on data generated in the object detectiondevice 210.

The HD map data may include detailed topology information in units oflanes of roads, connection information of each lane, and featureinformation for vehicle localization (e.g., traffic signs, lanemarking/attribute, road furniture, etc.). The HD map data may be basedon data received from an external server through the communicationdevice 220.

The dynamic data may include various types of dynamic information whichmay be generated on roads. For example, the dynamic data may includeconstruction information, variable speed road information, roadcondition information, traffic information, moving object information,etc. The dynamic data may be based on data received from an externalserver through the communication device 220. The dynamic data may bebased on data generated in the object detection device 210.

The processor 170 may provide map data in a range from a position atwhich the vehicle 10 is located to the horizon.

2.1.2) Horizon Path Data

The horizon path data may be explained as a trajectory through which thevehicle 10 may travel in a range from a position at which the vehicle 10is located to the horizon. The horizon path data may include dataindicating a relative probability of selecting a road at a decisionpoint (e.g., a fork, a junction, a crossroad, or the like). The relativeprobability may be calculated based on a time taken to arrive at a finaldestination. For example, if a time taken to arrive at a finaldestination is shorter when a first road is selected at a decision pointthan that when a second road is selected, a probability of selecting thefirst road may be calculated to be higher than a probability ofselecting the second road.

The horizon path data may include a main path and a sub-path. The mainpath may be understood as a trajectory obtained by connecting roadshaving a high relative probability of being selected. The sub-path maybe branched from at least one decision point on the main path. Thesub-path may be understood as a trajectory obtained by connecting atleast one road having a low relative probability of being selected at atleast one decision point on the main path.

3) Control Signal Generation Operation

The processor 170 may perform a control signal generation operation. Theprocessor 170 may generate a control signal based on the electronichorizon data. For example, the processor 170 may generate at least oneof a powertrain control signal, a brake device control signal, or asteering device control signal based on the electronic horizon data.

The processor 170 may transmit the generated control signal to thedriving control device 250 through the interface 180. The drivingcontrol device 250 may transmit the control signal to at least one of apowertrain 251, a brake device 252, or a steering device 253.

2. Cabin

FIG. 5 is a diagram showing the interior of the vehicle according toembodiment(s).

FIG. 6 is a block diagram referred to in description of a cabin systemfor a vehicle according to embodiment(s).

Referring to FIGS. 5 and 6, a cabin system 300 for a vehicle(hereinafter, a cabin system) may be defined as a convenience system fora user who uses the vehicle 10. The cabin system 300 may be explained asa high-end system including a display system 350, a cargo system 355, aseat system 360, and a payment system 365. The cabin system 300 mayinclude a main controller 370, a memory 340, an interface 380, a powersupply 390, an input device 310, an imaging device 320, a communicationdevice 330, the display system 350, the cargo system 355, the seatsystem 360, and the payment system 365. According to embodiments, thecabin system 300 may further include components in addition to thecomponents described in this specification or may not include some ofthe components described in this specification.

1) Main Controller

The main controller 370 may be electrically connected to the inputdevice 310, the communication device 330, the display system 350, thecargo system 355, the seat system 360, and the payment system 365 andexchange signals with these components. The main controller 370 maycontrol the input device 310, the communication device 330, the displaysystem 350, the cargo system 355, the seat system 360, and the paymentsystem 365. The main controller 370 may be implemented using at leastone of application specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, microcontrollers, microprocessors, orelectronic units for executing other functions.

The main controller 370 may be configured as at least onesub-controller. The main controller 370 may include a plurality ofsub-controllers according to an embodiment. Each of the sub-controllersmay individually control grouped devices and systems included in thecabin system 300. The devices and systems included in the cabin system300 may be grouped by functions or grouped based on seats on which auser may sit.

The main controller 370 may include at least one processor 371. AlthoughFIG. 6 illustrates the main controller 370 including a single processor371, the main controller 371 may include a plurality of processors. Theprocessor 371 may be categorized as one of the above-describedsub-controllers.

The processor 371 may receive signals, information, or data from a userterminal through the communication device 330. The user terminal maytransmit signals, information, or data to the cabin system 300.

The processor 371 may identify a user based on image data received fromat least one of an internal camera or an external camera included in theimaging device. The processor 371 may identify a user by applying animage processing algorithm to the image data. For example, the processor371 may identify a user by comparing information received from the userterminal with the image data. For example, the information may includeat least one of route information, body information, fellow passengerinformation, baggage information, position information, preferredcontent information, preferred food information, disability information,or use history information of a user.

The main controller 370 may include an artificial intelligence (AI)agent 372. The AI agent 372 may perform machine learning based on dataacquired through the input device 310. The AI agent 371 may control atleast one of the display system 350, the cargo system 355, the seatsystem 360, or the payment system 365 based on machine learning results.

2) Essential Components

The memory 340 is electrically connected to the main controller 370. Thememory 340 may store basic data about units, control data for operationcontrol of units, and input/output data. The memory 340 may store dataprocessed in the main controller 370. Hardware-wise, the memory 340 maybe configured using at least one of a ROM, a RAM, an EPROM, a flashdrive, or a hard drive. The memory 340 may store various types of datafor the overall operation of the cabin system 300, such as a program forprocessing or control of the main controller 370. The memory 340 may beintegrated with the main controller 370.

The interface 380 may exchange signals with at least one electronicdevice included in the vehicle 10 by wire or wirelessly. The interface380 may be configured using at least one of a communication module, aterminal, a pin, a cable, a port, a circuit, an element, or a device.

The power supply 390 may provide power to the cabin system 300. Thepower supply 390 may be provided with power from a power source (e.g., abattery) included in the vehicle 10 and supply the power to each unit ofthe cabin system 300. The power supply 390 may operate according to acontrol signal supplied from the main controller 370. For example, thepower supply 390 may be implemented as a switched-mode power supply(SMPS).

The cabin system 300 may include at least one PCB. The main controller370, the memory 340, the interface 380, and the power supply 390 may bemounted on at least one PCB.

3) Input Device

The input device 310 may receive user input. The input device 310 mayconvert the user input into an electrical signal. The electrical signalconverted by the input device 310 may be converted into a control signaland provided to at least one of the display system 350, the cargo system355, the seat system 360, or the payment system 365. The main controller370 or at least one processor included in the cabin system 300 maygenerate a control signal based on the electrical signal received fromthe input device 310.

The input device 310 may include at least one of a touch input unit, agesture input unit, a mechanical input unit, or a voice input unit. Thetouch input unit may convert a user's touch input into an electricalsignal. The touch input unit may include at least one touch sensor fordetecting a user's touch input. According to an embodiment, the touchinput unit may realize a touchscreen through integration with at leastone display included in the display system 350. Such a touchscreen mayprovide both an input interface and an output interface between thecabin system 300 and a user. The gesture input unit may convert a user'sgesture input into an electrical signal. The gesture input unit mayinclude at least one of an infrared sensor or an image sensor to sense auser's gesture input. According to an embodiment, the gesture input unitmay detect a user's three-dimensional gesture input. To this end, thegesture input unit may include a plurality of light output units foroutputting infrared light or a plurality of image sensors. The gestureinput unit may detect a user's three-dimensional gesture input usingTOF, structured light, or disparity. The mechanical input unit mayconvert a user's physical input (e.g., press or rotation) through amechanical device into an electrical signal. The mechanical input unitmay include at least one of a button, a dome switch, a jog wheel, or ajog switch. Meanwhile, the gesture input unit and the mechanical inputunit may be integrated. For example, the input device 310 may include ajog dial device that includes a gesture sensor and is formed such thatit may be inserted into/ejected from a part of a surrounding structure(e.g., at least one of a seat, an armrest, or a door). When the jog dialdevice is parallel to the surrounding structure, the jog dial device mayserve as a gesture input unit. When the jog dial device is protrudedfrom the surrounding structure, the jog dial device may serve as amechanical input unit. The voice input unit may convert a user's voiceinput into an electrical signal. The voice input unit may include atleast one microphone. The voice input unit may include a beam formingmicrophone.

4) Imaging Device

The imaging device 320 may include at least one camera. The imagingdevice 320 may include at least one of an internal camera or an externalcamera. The internal camera may capture an image of the inside of thecabin. The external camera may capture an image of the outside of thevehicle. The internal camera may acquire an image of the inside of thecabin. The imaging device 320 may include at least one internal camera.It is desirable that the imaging device 320 include as many cameras asthe number of passengers who can be accommodated in the vehicle. Theimaging device 320 may provide an image acquired by the internal camera.The main controller 370 or at least one processor included in the cabinsystem 300 may detect a motion of a user based on an image acquired bythe internal camera, generate a signal based on the detected motion, andprovide the signal to at least one of the display system 350, the cargosystem 355, the seat system 360, or the payment system 365. The externalcamera may acquire an image of the outside of the vehicle. The imagingdevice 320 may include at least one external camera. It is desirablethat the imaging device 320 include as many cameras as the number ofdoors through which passengers can enter the vehicle. The imaging device320 may provide an image acquired by the external camera. The maincontroller 370 or at least one processor included in the cabin system300 may acquire user information based on the image acquired by theexternal camera. The main controller 370 or at least one processorincluded in the cabin system 300 may authenticate a user or acquire bodyinformation (e.g., height information, weight information, etc.) of auser, fellow passenger information of a user, and baggage information ofa user based on the user information.

5) Communication Device

The communication device 330 may wirelessly exchange signals withexternal devices. The communication device 330 may exchange signals withexternal devices through a network or directly exchange signals withexternal devices. External devices may include at least one of a server,a mobile terminal, or another vehicle. The communication device 330 mayexchange signals with at least one user terminal. The communicationdevice 330 may include an antenna and at least one of an RF circuit oran RF element which may implement at least one communication protocol inorder to perform communication. According to an embodiment, thecommunication device 330 may use a plurality of communication protocols.The communication device 330 may switch communication protocolsaccording to a distance to a mobile terminal.

For example, the communication device may exchange signals with externaldevices based on cellular V2X (C-V2X). For example, C-V2X may includeLTE based sidelink communication and/or NR based sidelink communication.Details related to C-V2X will be described later.

For example, the communication device may exchange signals with externaldevices based on dedicated short range communications (DSRC) or wirelessaccess in vehicular environment (WAVE) based on IEEE 802.11p PHY/MAClayer technology and IEEE 1609 network/transport layer technology. DSRC(or WAVE) is communication specification for providing an intelligenttransport system (ITS) service through short-range dedicatedcommunication between vehicle-mounted devices or between a roadsidedevice and a vehicle-mounted device. DSRC may be a communication schemethat may use a frequency of 5.9 GHz and have a data transfer rate in therange of 3 Mbps to 27 Mbps. IEEE 802.11p may be combined with IEEE 1609to support DSRC (or WAVE).

The communication device of embodiment(s) may exchange signals withexternal devices using only one of C-V2X and DSRC. Alternatively, thecommunication device of embodiment(s) may exchange signals with externaldevices using a hybrid of C-V2X and DSRC.

6) Display System

The display system 350 may display graphical objects. The display system350 may include at least one display device. For example, the displaysystem 350 may include a first display device 410 for common use and asecond display device 420 for individual use.

6.1) Display Device for Common Use

The first display device 410 may include at least one display 411 whichoutputs visual content. The display 411 included in the first displaydevice 410 may be realized by at least one of a flat panel display, acurved display, a rollable display, or a flexible display. For example,the first display device 410 may include a first display 411 which ispositioned behind a seat and formed to be inserted/ejected into/from thecabin, and a first mechanism for moving the first display 411. The firstdisplay 411 may be disposed so as to be inserted into/ejected from aslot formed in a seat main frame. According to an embodiment, the firstdisplay device 410 may further include a flexible area controlmechanism. The first display may be formed to be flexible and a flexiblearea of the first display may be controlled according to user position.For example, the first display device 410 may be disposed on the ceilinginside the cabin and include a second display formed to be rollable anda second mechanism for rolling or unrolling the second display. Thesecond display may be formed such that images may be displayed on bothsides thereof. For example, the first display device 410 may be disposedon the ceiling inside the cabin and include a third display formed to beflexible and a third mechanism for bending or unbending the thirddisplay. According to an embodiment, the display system 350 may furtherinclude at least one processor which provides a control signal to atleast one of the first display device 410 or the second display device420. The processor included in the display system 350 may generate acontrol signal based on a signal received from at least one of the maincontroller 370, the input device 310, the imaging device 320, or thecommunication device 330.

A display area of a display included in the first display device 410 maybe divided into a first area 411 a and a second area 411 b. The firstarea 411 a may be defined as a content display area. For example, thefirst area 411 may display at least one of graphical objectscorresponding to entertainment content (e.g., movies, sports, shopping,music, etc.), video conferences, food menus, or augmented realityscreens. The first area 411 a may display graphical objectscorresponding to traveling situation information of the vehicle 10. Thetraveling situation information may include at least one of objectinformation outside the vehicle, navigation information, or vehiclestate information. The object information outside the vehicle mayinclude information about presence or absence of an object, positionalinformation of the object, information about a distance between thevehicle and the object, and information about a relative speed of thevehicle with respect to the object. The navigation information mayinclude at least one of map information, information about a setdestination, route information according to setting of the destination,information about various objects on a route, lane information, orinformation about the current position of the vehicle. The vehicle stateinformation may include vehicle attitude information, vehicle speedinformation, vehicle tilt information, vehicle weight information,vehicle orientation information, vehicle battery information, vehiclefuel information, vehicle tire pressure information, vehicle steeringinformation, vehicle indoor temperature information, vehicle indoorhumidity information, pedal position information, vehicle enginetemperature information, etc. The second area 411 b may be defined as auser interface area. For example, the second area 411 b may display anAI agent screen. The second area 411 b may be located in an area definedby a seat frame according to an embodiment. In this case, a user mayview content displayed in the second area 411 b between seats. The firstdisplay device 410 may provide hologram content according to anembodiment. For example, the first display device 410 may providehologram content for each of a plurality of users such that only a userwho requests the content may view the content.

6.2) Display Device for Individual Use

The second display device 420 may include at least one display 421. Thesecond display device 420 may provide the display 421 at a position atwhich only an individual passenger may view display content. Forexample, the display 421 may be disposed on an armrest of a seat. Thesecond display device 420 may display graphic objects corresponding topersonal information of a user. The second display device 420 mayinclude as many displays 421 as the number of passengers who may ride inthe vehicle. The second display device 420 may realize a touchscreen byforming a layered structure along with a touch sensor or beingintegrated with the touch sensor. The second display device 420 maydisplay graphical objects for receiving user input for seat adjustmentor indoor temperature adjustment.

7) Cargo System

The cargo system 355 may provide items to a user at the request of theuser. The cargo system 355 may operate based on an electrical signalgenerated by the input device 310 or the communication device 330. Thecargo system 355 may include a cargo box. The cargo box may be hidden,with items being loaded in a part under a seat. When an electricalsignal based on user input is received, the cargo box may be exposed tothe cabin. The user may select a necessary item from articles loaded inthe cargo box. The cargo system 355 may include a sliding movingmechanism and an item pop-up mechanism in order to expose the cargo boxaccording to user input. The cargo system 355 may include a plurality ofcargo boxes in order to provide various types of items. A weight sensorfor determining whether each item is provided may be embedded in thecargo box.

8) Seat System

The seat system 360 may provide a user customized seat to a user. Theseat system 360 may operate based on an electrical signal generated bythe input device 310 or the communication device 330. The seat system360 may adjust at least one element of a seat based on acquired userbody data. The seat system 360 may include a user detection sensor(e.g., a pressure sensor) for determining whether a user sits on a seat.The seat system 360 may include a plurality of seats on which aplurality of users may sit. One of the plurality of seats may bedisposed to face at least one other seat. At least two users may setfacing each other inside the cabin.

9) Payment System

The payment system 365 may provide a payment service to a user. Thepayment system 365 may operate based on an electrical signal generatedby the input device 310 or the communication device 330. The paymentsystem 365 may calculate a price for at least one service used by theuser and request the user to pay the calculated price.

3. C-V2X

A wireless communication system is a multiple access system thatsupports communication with multiple users by sharing available systemresources (for example, bandwidth, transmit power, or the like).Examples of the multiple access system include a code division multipleaccess (CDMA) system, a frequency division multiple access (FDMA)system, a time division multiple access (TDMA) system, an orthogonalfrequency division multiple access (OFDMA) system, and a single carrierfrequency division multiple access (SC-FDMA) system, a multi-carrierfrequency division multiple access (MC-FDMA) system and the like.

Sidelink refers to a communication method of establishing a direct linkbetween user equipments (UEs) and directly exchanging voice, data, orthe like between terminals without passing through a base station (BS).The sidelink is considered as one way to solve a burden of the BS due torapidly increasing data traffic.

Vehicle-to-everything (V2X) refers to a communication technology thatexchanges information with other vehicles, pedestrians, things for whichinfrastructure is built, and the like through wired/wirelesscommunication. The V2X may be classified into four types such asvehicle-to-vehicle (V2V), vehicle-to-infrastructure (V21),vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2Xcommunication may be provided via a PC5 interface and/or a Uu interface.

Meanwhile, as more communication devices require larger communicationcapacities, there is a need for improved mobile broadband communicationas compared to existing radio access technology (RAT). Accordingly, acommunication system considering a service or a terminal that issensitive to reliability and latency is being discussed. Next-generationradio access technologies that consider improved mobile broadbandcommunication, massive MTC, ultra-reliable and low-latency communication(URLLC), and the like may be referred to as new RAT or new radio (NR).Vehicle-to-everything (V2X) communication may be supported even in NR.

The following technologies may be used for various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), andsingle carrier frequency division multiple access (SC-FDMA). CDMA may beimplemented by wireless technologies such as universal terrestrial radioaccess (UTRA) and CDMA2000. TDMA may be implemented by wirelesstechnologies such as global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). OFDMA may be implemented by wireless technologies suchas institute of electrical and electronics engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and evolved UTRA (E-UTRA).IEEE 802.16m is an evolution of IEEE 802.16e and provides backwardcompatibility with systems based on IEEE 802.16e. UTRA is part of auniversal mobile telecommunications system (UMTS). 3rd generationpartnership project (3GPP) long term evolution (LTE) is part of evolvedUMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), andemploys OFDMA on downlink and SC-FDMA on uplink. LTE-advanced (LTE-A) isan evolution of 3GPP LTE.

5G NR is a successor technology to LTE-A, and is a new clean-slate typemobile communication system having characteristics such as highperformance, low latency, and high availability. 5G NR may takeadvantage of all available spectral resources such as a low frequencyband below 1 GHz, an intermediate frequency band from 1 GHz to 10 GHz,and a high frequency (millimeter wave) band above 24 GHz.

For clarity of description, the following description focuses on LTE-Aor 5G NR, but the technical idea of embodiment(s) is not limitedthereto.

FIG. 7 illustrates the structure of an LTE system to which embodiment(s)are applicable. This system may be referred to as an evolved-UMTSterrestrial radio access network (E-UTRAN) or long-term evolution(LTE)/LTE-advanced (LTE-A) system.

Referring to FIG. 7, the E-UTRAN includes a base station 20 thatprovides a control plane and a user plan to a user equipment (UE) 10.The UE 10 may be fixed or mobile. The UE 10 may be referred to byanother term, such as a mobile station (MS), a user terminal (UT), asubscriber station (SS), a mobile terminal (MT), a wireless device, etc.The BS 20 refers to a fixed station that communicates with the UE 10.The BS 20 may be referred to by another term, such as an evolved-NodeB(eNB), a base transceiver system (BTS), an access point, etc.

BSs 20 may be connected to each other through an X2 interface. The BS 20is connected to an evolved packet core (EPC) 30 through an S1 interface,more specifically, to a mobility management entity (MME) through S1-MMEand to a serving gateway (S-GW) through S1-U.

The EPC 30 includes the MME, the S-GW, and a packet data network (PDN)gateway (P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having the E-UTRANas an end point. The P-GW is a gateway having the PDN as an end point.

Layers of a radio interface protocol between the UE and the network maybe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) reference model that is well-known in acommunication system. Thereamong, a physical layer belonging to thefirst layer provides an information transfer service using a physicalchannel, and a radio resource control (RRC) layer belonging to the thirdlayer serves to control a radio resource between the UE and the network.For this, the RRC layer exchanges an RRC message between the UE and theBS.

FIG. 8 illustrates a radio protocol architecture for a user plane towhich embodiment(s) are applicable.

FIG. 9 illustrates a radio protocol architecture for a control plane towhich embodiment(s) are applicable. The user plane is a protocol stackfor user data transmission. The control plane is a protocol stack forcontrol signal transmission.

Referring to FIGS. 8 and 9, a physical layer provides an upper layerwith an information transfer service through a physical channel. Thephysical layer is connected to a media access control (MAC) layer, whichis an upper layer of the physical layer, through a transport channel.Data is transferred between the MAC layer and the physical layer throughthe transport channel. The transport channel is classified according tohow and with which characteristics data is transferred through a radiointerface.

Data is moved between different physical layers, i.e., between thephysical layers of a transmitter and a receiver, through a physicalchannel. The physical channel may be modulated according to anorthogonal frequency division multiplexing (OFDM) scheme and use timeand frequency as radio resources.

The MAC layer provides a service to a radio link control (RLC) layer,which is an upper layer, through a logical channel. The MAC layerprovides a mapping function from a plurality of logical channels to aplurality of transport channels. The MAC layer also provides a logicalchannel multiplexing function caused by mapping from a plurality oflogical channels to a single transport channel. A MAC sublayer providesdata transfer services on logical channels.

The RLC layer performs concatenation, segmentation, and reassembly of anRLC service data unit (SDU). In order to guarantee various types ofquality of service (QoS) required by a radio bearer (RB), the RLC layerprovides three operation modes: transparent mode (TM), unacknowledgedmode (UM), and acknowledged mode (AM). AM RLC provides error correctionthrough an automatic repeat request (ARQ).

The RRC layer is defined only in the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of RBs toserve to control logical channels, transport channels, and physicalchannels. The RB means a logical path provided by the first layer(physical layer) and the second layer (MAC layer, RLC layer, or PDCPlayer) in order to transfer data between a UE and a network.

A function of a packet data convergence protocol (PDCP) layer in theuser plane includes transfer, header compression, and ciphering of userdata. A function of the PDCP layer in the control plane includestransfer and encryption/integrity protection of control plane data.

The configuration of the RB means a process of defining thecharacteristics of a radio protocol layer and channels in order toprovide specific service and configuring each detailed parameter andoperating method. The RB may be divided into two types of a signaling RB(SRB) and a data RB (DRB). The SRB is used as a passage through which anRRC message is transported in the control plane, and the DRB is used asa passage through which user data is transported in the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of the E-UTRAN, the UE is in an RRC connected (RRC_CONNECTED)state and if not, the UE is in an RRC idle (RRC_IDLE) state. In NR, anRRC inactive (RRC_INACTIVE) state has been further defined. The UE ofRRC_INACTIVE state may release connection to the BS while maintainingconnection to a core network.

A downlink transport channel through which data is transmitted from thenetwork to the UE includes a broadcast channel (BCH) through whichsystem information is transmitted and a downlink shared channel (SCH)through which user traffic or control messages are transmitted. Trafficor a control message for a downlink multicast or broadcast service maybe transmitted through the downlink SCH or may be transmitted through aseparate downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from the UE to thenetwork includes a random access channel (RACH) through which an initialcontrol message is transmitted and an uplink shared channel (SCH)through which user traffic or a control message is transmitted.

Logical channels that are placed over the transport channel and mappedto the transport channel include a broadcast control channel (BCCH), apaging control channel (PCCH), a common control channel (CCCH), amulticast control channel (MCCH), and a multicast traffic channel(MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. A resource block is aresources allocation unit and includes a plurality of OFDM symbols and aplurality of subcarriers. Each subframe may use specific subcarriers ofspecific OFDM symbols (e.g., the first OFDM symbol) of a correspondingsubframe for a physical downlink control channel (PDCCH), that is, anL1/L2 control channel. A transmission time interval (TTI) is a unit timefor subframe transmission.

FIG. 10 illustrates the structure of an NR system to which embodiment(s)are applicable.

Referring to FIG. 10, a next generation radio access network (NG-RAN)may include a gNB and/or an eNB that provides user plane and controlplane protocol terminations to a UE. FIG. 10 illustrates the case ofincluding only gNBs. The gNB and the eNB are connected through an Xninterface. The gNB and the eNB are connected to a 5G core network (5GC)via an NG interface. More specifically, the gNB and the eNB areconnected to an access and mobility management function (AMF) via anNG-C interface and connected to a user plane function (UPF) via an NG-Uinterface.

FIG. 11 illustrates functional split between an NG-RAN and a 5GC towhich embodiment(s) are applicable.

Referring to FIG. 11, a gNB may provide functions, such as intercellradio resource management (RRM), RB control, connection mobilitycontrol, radio admission control, measurement configuration andprovision, dynamic resource allocation, etc. An AMF may providefunctions, such as NAS security, idle state mobility handling, etc. AUPF may provide functions, such as mobility anchoring, protocol dataunit (PDU) handling, etc. A session management function (SMF) mayprovide functions, such as UE IP address allocation, PDU sessioncontrol.

FIG. 12 illustrates the structure of an NR radio frame to whichembodiment(s) are applicable.

Referring to FIG. 12, a radio frame may be used for uplink and downlinktransmission in NR. The radio frame is 10 ms long and may be defined astwo half-frames (HFs), each 5 ms long. An HF may include 5 subframes(SFs), each 1 ms long. An SF may be split into one or more slots. Thenumber of slots in the SF may be determined based on a subcarrierspacing (SCS). Each slot may include 12 or 14 OFDM(A) symbols dependingon a cyclic prefix (CP).

When a normal CP is used, each slot may include 14 symbols. When anextended CP is used, each slot may include 12 symbols. Here, a symbolmay include an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol (orDFT-s-OFDM symbol).

Table 1 below shows the number of symbols, N^(slot) _(symb), per slot,the number of slots, N^(frame,u) _(slot), per frame, and the number ofslots, N^(subframe,u) _(slot), per subframe according to SCSconfiguration μ when the normal CP is used.

TABLE 1 SCS (15*2u) N^(slot) _(symb) N^(frame, u) _(slot)N^(subframe, u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60KHz (u = 2) 14 40 4 120 KHz (u = 3)  14 80 8 240 KHz (u = 4)  14 160 16

Table 2 shows the number of symbols per slot, the number of slots perframe, and the number of slots per subframe according to SCS when theextended CP is used.

TABLE 2 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame, u)_(slot) N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4

In an NR system, different OFDM(A) numerologies (e.g., SCSs and CPlengths) may be configured in a plurality of cells aggregated for oneUE. Then, an (absolute time) duration of a time resource (e.g., asubframe, a slot, or a TTI) consisting of the same number of symbols(for convenience, referred to as a time unit (TU)) may be differentlyconfigured in the aggregated cells.

FIG. 13 illustrates the structure of a slot of an NR frame to whichembodiment(s) are applicable.

Referring to FIG. 13, a slot includes a plurality of symbols in the timedomain. For example, one slot may include 14 symbols in the case of anormal CP and 12 symbols in the case of an extended CP. Alternatively,one slot may include 7 symbols in the case of the normal CP and 6symbols in the case of the extended CP.

A carrier includes a plurality of subcarriers in the frequency domain. Aresource block (RB) may be defined as a plurality of consecutivesubcarriers (e.g., 12 subcarriers) in the frequency domain. A bandwidthpart (BWP) may be defined as a plurality of consecutive (P)RBs in thefrequency domain and correspond to one numerology (e.g., SCS or CPlength). The carrier may include a maximum of N (e.g., 5) BWPs. Datacommunication may be performed through activated BWPs. Each element maybe referred to as a resource element (RS) in a resource grid and onecomplex symbol may be mapped thereto.

As illustrated in FIG. 14, a scheme of reserving a transmission resourceof a subsequent packet may be used for transmission resource selection.

FIG. 14 illustrates an example of selecting a transmission resource towhich embodiments(s) are applicable.

In V2X communication, two transmissions may be performed per MAC PDU.For example, referring to FIG. 14, during resource selection for initialtransmission, a resource for retransmission may be reserved with apredetermined time gap. A UE may discern transmission resources reservedby other UEs or resources that are being used by other UEs throughsensing within a sensing window and randomly select a resource havingless interference from among resources that remain after excluding theresources that are reserved or being used by other UEs within aselection window.

For example, the UE may decode a physical sidelinik control channel(PSCCH) including information about periodicity of the reservedresources within the sensing window and measure physical sidelink sharedchannel (PSSCH) reference signal received power (RSRP) on periodicallydetermined resources based on the PSCCH. The UE may exclude resources onwhich PSSCH RSRP exceeds a threshold from resources that are selectablein the selection window. Next, the UE may randomly select a sidelinkresource from among resources that remain within the selection window.

Alternatively, the UE may measure a received signal strength indicator(RSSI) of periodic resources within the sensing window to determineresources having less interference (e.g., resources having lowinterference corresponding to 20% or less). Then, the UE may randomlyselect a sidelink resource from resources included in the selectionwindow among the periodic resources. For example, upon failing to decodethe PSCCH, the UE may use this method.

FIG. 15 illustrates an example of transmitting a PSCCH in sidelinktransmission mode 3 or 4 to which embodiment(s) are applicable.

In V2X communication, i.e., in sidelink transmission mode 3 or 4, aPSCCH and a PSSCH are transmitted through frequency divisionmultiplexing (FDM) as opposed to sidelink communication. In V2Xcommunication, since it is important to reduce latency in considerationof characteristics of vehicle communication, the PSCCH and the PSSCH maybe transmitted through FDM on different frequency resources of the sametime resource in order to reduce latency. Referring to FIG. 15, thePSCCH and the PSSCH may be non-adjacent as illustrated in (a) of FIG. 15or may be adjacent as illustrated in (b) of FIG. 15. A basic unit ofsuch transmission is a subchannel. The subchannel may be a resource unithaving one or more RBs in size on the frequency axis on a predeterminedtime resource (e.g., time resource unit). The number of RBs included inthe subchannel (i.e., the size of the subchannel and a start position ofthe subchannel on the frequency axis) may be indicated through higherlayer signaling. An embodiment of FIG. 15 may also be applied to NRsidelink resource allocation mode 1 or 2.

Hereinafter, a cooperative awareness message (CAM) and a decentralizedenvironmental notification message (DENM) will be described.

In V2V communication, a CAM of a periodic message type and a DENM of anevent triggered message type may be transmitted. The CAM may includebasic vehicle information, including vehicle dynamic state informationsuch as direction and speed, vehicle static data such as dimension, anexternal light state, and a path history. The size of the CAM may be 50to 300 bytes. The CAM may be broadcast and latency should be less than100 ms. The DENM may be a message generated during an unexpectedsituation such as breakdown or accident of a vehicle. The size of theDENM may be shorter than 3000 bytes and all vehicles in the range ofmessage transmission may receive the DENM. The DENM may have a higherpriority than the CAM.

Hereinafter, carrier reselection will be described.

Carrier reselection for V2X/sidelink communication may be performed in aMAC layer based on a channel busy ratio (CBR) of configured carriers anda ProSe-per-packet priority (PPPP) of a V2X message to be transmitted.

The CBR may mean the portion of subchannels in a resource pool, sidelinkRSSI (S-RSSI) of which measured by a UE is sensed as exceeding a presetthreshold. There may be PPPP related to each logical channel. The valueof PPPP should be set in consideration of latency required by both a UEand a BS. During carrier reselection, the UE may select one or morecarriers from among candidate carriers in ascending order from thelowest CBR.

Hereinafter, physical layer processing will be described.

A data unit to which embodiment(s) are applicable may be a target ofphysical layer processing in a transmitting side before the data unit istransmitted through a radio interface. A radio signal carrying the dataunit to which embodiment(s) are applicable may be a target of physicallayer processing at a receiving side.

FIG. 16 illustrates an example of physical processing at a transmittingside to which embodiment(s) are applicable.

Table 3 shows a mapping relationship between an uplink transport channeland a physical channel and Table 4 shows a mapping relationship betweenuplink control channel information and a physical channel.

TABLE 3 Transport Channel Physical Channel UL-SCH PUSCH RACH PRACH

TABLE 4 Control Information Physical Channel UCI PUCCH, PUSCH

Table 5 shows a mapping relationship between a downlink transportchannel and a physical channel and Table 6 shows a mapping relationshipbetween downlink control channel information and a physical channel.

TABLE 5 Transport Channel Physical Channel DL-SCH PDSCH BCH PBCH PCHPDSCH

TABLE 6 Control Information Physical Channel DCI PDCCH

Table 7 shows a mapping relationship between a sidelink transportchannel and a physical channel and Table 8 shows a mapping relationshipbetween sidelink control channel information and a physical channel.

TABLE 7 Transport Channel Physical Channel SL-SCH PSSCH SL-BCH PSBCH

TABLE 8 Control Information Physical Channel SCI PSCCH

Referring to FIG. 17, the transmitting side may perform encoding on atransport block (TB) in step S100. Data and a control stream from a MAClayer may be encoded to provide transport and control services through aradio transmission link in a physical layer. For example, the TB fromthe MAC layer may be encoded to a codeword at the transmitting side. Achannel coding scheme may be a combination of error detection, errorcorrection, rate matching, interleaving, and control information or atransport channel separated from the physical channel. Alternatively,the channel coding scheme may be a combination of error detection, errorcorrection, rate matching, interleaving, and control information or atransport channel mapped to the physical channel.

In an NR LTE system, the following channel coding scheme may be used fordifferent types of transport channels and different types of controlinformation. For example, the channel coding scheme for each transportchannel type may be listed in Table 9. For example, the channel codingscheme for each control information type may be listed in Table 10.

TABLE 9 Transport Channel Channel Coding Scheme UL-SCH LDPC (Low DensityParity Check) DL-SCH SL-SCH PCH BCH Polar code SL-BCH

TABLE 10 Control Information Channel Coding Scheme DCI Polar code SCIUCI Block code, Polar code

For transmission of the TB (e.g., MAC PDU), the transmitting side mayattach a cyclic redundancy check (CRC) sequence to the TB. Therefore,the transmitting side may provide error detection to the receiving side.In sidelink communication, the transmitting side may be a transmittingUE and the receiving side may be a receiving UE. In the NR system, acommunication device may use an LDPC code to encode/decode an uplink(UL)-SCH and a downlink (DL)-SCH. The NR system may support two LDPCbase graphs (i.e., two LDPC base matrices). The two LDPC base graphs maybe LDPC base graph 1 optimized for a small TB and LDPC base graph 2optimized for a large TB. The transmitting side may select LDPC basegraph 1 or 2 based on the size of the TB and a code rate R. The coderate may be indicated by a modulation and coding scheme (MCS) indexI_MCS. The MCS index may be dynamically provided to the UE by a PDCCHthat schedules a PUSCH or a PDSCH. Alternatively, the MCS index may bedynamically provided to the UE by a PDCCH that (re)initializes oractivates UL configured grant 2 or DL semi-persistent scheduling (SPS).The MCS index may be provided to the UE by RRC signaling related to ULconfigured grant type 1. If the TB to which the CRC is attached isgreater than a maximum code block size for the selected LDPC base graph,the transmitting side may segment the TB to which the CRC is attachedinto a plurality of code blocks. The transmitting side may attach anadditional CRC sequence to each code block. A maximum code block sizefor LDPC base graph 1 and a maximum code block size for LDPC base graph2 may be 8448 bits and 3480 bits, respectively. If the TB to which theCRC is attached is not greater than the maximum code block size for theselected LDPC base graph, the transmitting side may encode the TB towhich the CRC is attached using the selected LDPC base graph. Thetransmitting side may encode each code block of the TB using theselected LDPC base graph. LDPC coded blocks may be individuallyrate-matched. Code block concatenation may be performed to generate acodeword for transmission on the PDSCH or the PUSCH. For the PDSCH, amaximum of two codewords (i.e., a maximum of two TBs) may besimultaneously transmitted on the PDSCH. The PUSCH may be used totransmit UL-SCH data and layer 1 and/or 2 control information. Althoughnot illustrated in FIG. 17, the layer 1 and/or 2 control information maybe multiplexed with a codeword for the UL-SCH data.

In steps S101 and S102, the transmitting side may perform scrambling andmodulation for the codeword. Bits of the codeword may be scrambled andmodulated to generate a block of complex-valued modulation symbols.

In step S103, the transmitting side may perform layer mapping. Thecomplex-valued modulation symbols of the codeword may be mapped to oneor more multiple input multiple output (MIMO) layers. The codeword maybe mapped to a maximum of 4 layers. The PDSCH may carry two codewordsand thus the PDSCH may support up to 8-layer transmission. The PUSCH maysupport a single codeword and thus the PUSCH may support up to 4-layertransmission.

In step S104, the transmitting side may perform transform precoding. ADL transmission waveform may be a normal CP-OFDM waveform. Transformprecoding (i.e., discrete Fourier transform (DFT)) may not be applied toDL.

A UL transmission waveform may be legacy OFDM using a CP having atransform precoding function performing DFT spreading, which may bedisabled or enabled. In the NR system, if the transform precodingfunction is enabled on UL, transform precoding may be selectivelyapplied. Transform precoding may spread UL data in a special manner inorder to reduce a peak-to-average power ratio (PAPR) of a waveform.Transform precoding may be one type of DFT. That is, the NR system maysupport two options for a UL waveform. One option may be CP-OFDM (whichis the same as a DL waveform) and the other option may be DFT spreadOFDM (DFT-s-OFDM). Whether the UE should use CP-OFDM or DFT-s-OFDM maybe determined by the BS through an RRC parameter.

In step S105, the transmitting side may perform subcarrier mapping. Alayer may be mapped to an antenna port. On DL, transparent manner(non-codebook-based) mapping may be supported for layer-to-antenna portmapping. How beamforming or MIMO precoding is performed may betransparent to the UE. On UL, both non-codebook-based mapping andcodebook-based mapping may be supported for antenna port mapping.

For each antenna port (i.e., layer) used for transmission of a physicalchannel (e.g., a PDSCH, a PUSCH, or a PSSCH), the transmitting side maymap complex-valued modulation symbols to subcarriers in an RB allocatedto the physical channel.

In step S106, the transmitting side may perform OFDM modulation. Acommunication device of the transmitting side may generate a subcarrierspacing configuration u for a time-continuous OFDM baseband signal on anantenna port p and an OFDM symbol 1 in a TTI for the physical channel byadding the CP and performing inverse fast Fourier transform (IFFT). Forexample, the communication device of the transmitting side may performIFFT on a complex-valued modulation symbol mapped to an RB of acorresponding OFDM symbol with respect to each OFDM symbol. Thecommunication device of the transmitting side may add the CP to an IFFTsignal in order to generate the OFDM baseband signal.

In step S107, the transmitting side may perform up-conversion. Thecommunication device of the transmitting side may perform up-conversionon the OFDM baseband signal for the antenna port p, the subcarrierspacing configuration u, and the OFDM symbol into a carrier frequency f0of a cell to which the physical channel is allocated.

Processors 9011 and 9021 of FIG. 34 may be configured to performencoding, scrambling, modulation, layer mapping, transform precoding (onUL), subcarrier mapping, and OFDM modulation.

FIG. 17 illustrates an example of physical layer processing at areceiving side to which embodiment(s) are applicable.

Physical layer processing at the receiving side may be basically thereverse of physical layer processing at the transmitting side.

In step S110, the receiving side may perform frequency down-conversion.A communication device of the receiving side may receive an RF signal ofa carrier frequency through an antenna. Transceivers 9013 and 9023 forreceiving the RF signal in the carrier frequency may down-convert thecarrier frequency of the RF signal into a baseband signal in order toobtain an OFDM baseband signal.

In step S111, the receiving side may perform OFDM demodulation. Thecommunication device of the receiving side may acquire a complex-valuedmodulation symbol through CP detachment and FFT. For example, thecommunication device of the receiving side may detach a CP from the OFDMbaseband signal with respect to each OFDM symbol. The communicationdevice of the receiving side may perform FFT on the CP-detached OFDMbaseband signal in order to acquire the complex-valued modulation symbolfor an antenna port p, a subcarrier spacing u, and an OFDM symbol 1.

In step S112, the receiving side may perform subcarrier demapping.Subcarrier demapping may be performed on the complex-valued modulationsymbol in order to acquire a complex-valued modulation symbol of acorresponding physical channel. For example, the processor of the UE mayacquire a complex-valued modulation symbol mapped to a subcarrierbelonging to a PDSCH among complex-valued modulation symbols received ina bandwidth part (BWP).

In step S113, the receiving side may perform transform deprecoding. Iftransform precoding is enabled with respect to a UL physical channel,transform deprecoding (e.g., inverse discrete Fourier transform (IDFT))may be performed on a complex-valued modulation symbol of the ULphysical channel. Transform deprecoding may not be performed on a DLphysical channel and a UL physical channel for which transform precodingis disabled.

In step S114, the receiving side may perform layer demapping. Acomplex-valued modulation symbol may be demapped to one or twocodewords.

In steps S115 and S116, the receiving side may perform demodulation anddescrambling, respectively. A complex-valued modulation symbol of acodeword may be demodulated and may be descrambled to a bit of thecodeword.

In step S117, the receiving side may perform decoding. A codeword may bedecoded to a TB. For a UL-SCH and a DL-SCH, LDPC base graph 1 or 2 maybe selected based on the size of a TB and a code rate R. The codewordmay include one or multiple coded blocks. Each coded block may bedecoded to a code block to which a CRC is attached or a TB to which theCRC is attached using the selected LDPC base graph. If the transmittingside performs code block segmentation on the TB to which the CRC isattached, a CRC sequence may be eliminated from each of code blocks towhich the CRC is attached and code blocks may be acquired. A code blockmay be concatenated to the TB to which the CRC is attached. A TB CRCsequence may be detached from the TB to which the CRC is attached andthen the TB may be acquired. The TB may be transmitted to a MAC layer.

The processors 9011 and 9021 of FIG. 20 may be configured to performOFDM demodulation, subcarrier demapping, layer demapping, demodulation,descrambling, and decoding.

In physical layer processing at the transmitting/receiving sidedescribed above, time and frequency domain resource related tosubcarrier mapping (e.g., an OFDM symbol, a subcarrier, or a carrierfrequency), and OFDM modulation and frequency up/down-conversion may bedetermined based on resource allocation (e.g., UL grant or DLallocation).

Hereinafter, synchronization acquisition of a sidelink UE will bedescribed.

In a time division multiple access (TDMA) and frequency divisionmultiples access (FDMA) system, accurate time and frequencysynchronization is essential. If time and frequency synchronization isnot accurately established, system performance may be deteriorated dueto inter-symbol interference (ISI) and inter-carrier interference (ICI).This is equally applied even to V2X. For time/frequency synchronizationin V2X, a sidelink synchronization signal (SLSS) may be used in aphysical layer and master information block-sidelink-V2X (MIB-SL-V2X)may be used in a radio link control (RLC) layer.

FIG. 18 illustrates a synchronization source or synchronizationreference in V2X to which embodiment(s) are applicable.

Referring to FIG. 18, in V2X, a UE may be directly synchronized with aglobal navigation satellite system (GNSS) or may be indirectlysynchronized with the GNSS through the UE (in network coverage or out ofnetwork coverage) that is directly synchronized with the GNSS. If theGNSS is configured as a synchronization source, the UE may calculate adirect frame number (DFN) and a subframe number using coordinateduniversal time (UTC) and a (pre)configured DFN offset.

Alternatively, the UE may be directly synchronized with a BS or may besynchronized with another UE that is synchronized in time/frequency withthe BS. For example, the BS may be an eNB or a gNB. For example, whenthe UE is in network coverage, the UE may receive synchronizationinformation provided by the BS and may be directly synchronized with theBS. Next, the UE may provide the synchronization information to adjacentanother UE. If a timing of the BS is configured as the synchronizationreference, the UE may conform to a cell related to a correspondingfrequency (when the UE is in cell coverage in the frequency) or aprimary cell or a serving cell (when the UE is out of cell coverage inthe frequency), for synchronization and DL measurement.

The BS (e.g., serving cell) may provide a synchronization configurationfor a carrier used for V2X/sidelink communication. In this case, the UEmay conform to the synchronization configuration received from the BS.If the UE fails to detect any cell in the carrier used for V2X/sidelinkcommunication and fails to receive the synchronization configurationfrom the serving cell, the UE may conform to a preset synchronizationconfiguration.

Alternatively, the UE may be synchronized with another UE that hasfailed to directly or indirectly acquire the synchronization informationfrom the BS or the GNSS. A synchronization source and a preferencedegree may be preconfigured for the UE. Alternatively, thesynchronization source and the preference degree may be configuredthrough a control message provided by the BS.

The sidelink synchronization source may be associated with asynchronization priority level. For example, a relationship between thesynchronization source and the synchronization priority level may bedefined as shown in Table 11. Table 11 is purely exemplary and therelationship between the synchronization source and the synchronizationpriority level may be defined in various manners.

TABLE 11 Priority GNSS-based eNB/gNB-based Level SynchronizationSynchronization P0 GNSS eNB/gNB P1 All UEs directly All UEs directlysynchronized with GNSS synchronized with eNB/gNB P2 All UEs indirectlyAll UEs indirectly synchronized with GNSS synchronized with eNB/gNB P3All other UEs GNSS P4 N/A All UEs directly synchronized with GNSS P5 N/AAll UEs indirectly synchronized with GNSS P6 N/A All other UEs

Whether to use GNSS-based synchronization or eNB/gNB-basedsynchronization may be (pre)configured. In a single-carrier operation,the UE may derive a transmission timing thereof from an availablesynchronization reference having the highest priority.

As described above, in existing sidelink communication, the GNSS, theeNB, and the UE may be configured/selected as the synchronizationreference. In case of NR, the gNB has been introduced, so the NR gNB mayalso be the synchronization reference and then it is necessary todetermine a synchronization source priority of the gNB. In addition, theNR UE may neither implement an LTE synchronization signal detector noraccess an LTE carrier (non-standalone NR UE). In this situation, the LTEUE and the NR UE may have different timings, which is not desirable inview of effective resource allocation. For example, if the LTE UE andthe NR UE operate at different timings, one TTI may partially overlap,resulting in unstable interference therebetween, or some (overlapping)TTIs may not be used for transmission and reception. Accordingly,hereinafter, various embodiments of how to configure the synchronizationreference in a situation in which the NR gNB and the LTE eNB coexistwill be described based on the above description. In the followingdescription, the synchronization source/reference may be defined as asynchronization signal used by the UE to transmit and receive a sidelinksignal or derive a timing for a subframe boundary, or as a subject thattransmit the synchronization signal. If the UE derives the subframeboundary based on a UTC timing derived from the GNSS by receiving a GNSSsignal, the GNSS signal or the GNSS may be the synchronizationsource/reference.

Meanwhile, in direct V2V communication, the UE transmits a messagewithin a predetermined time for the purpose of safety or infotainment.In this case, each message has a target arrival distance. For example, amessage of a specific application/service may require a short arrivaldistance and a message of another specific application/service mayrequire a long arrival distance. Meanwhile, even for the same service, arequired arrival distance may be different according to the moving speedor location of the UE. For example, a fast moving UE and a slow movingUE may have different latency requirements or arrival distances formessage delivery.

Initial Access (IA)

For a process of connecting the BS and the UE, the BS and the UE(transmitting/receiving UE) may perform an initial access (IA)operation.

Cell Search

For cell search, the UE should make some assumptions. The UE shouldassume that an SSS, a physical broadcast channel (PBCH) demodulationreference signal (DM-RS), and PBCH data have the same energy perresource element (EPRE). The UE may assume that the ratio of PSS EPRE toSSS EPRE in an SS/PBCH block of a corresponding cell is 0 dB or 3 dB.

A cell search procedure of the UE is a procedure of acquiring time andfrequency synchronization with a cell and detecting a physical layercell ID of the cell as shown in Table 12. The UE receives asynchronization signal (SS), a primary synchronization signal (PSS), anda secondary synchronization signal (SSS) in order to perform cellsearch.

The UE may receive an SS/PBCH block in symbols in which receptiontimings of the PBCH, the PSS, and the SSS are contiguous.

TABLE 12 Type of Signals Operations 1^(st) step PSS SS/PBCH block (SSB)symbol timing\acquisition Cell ID detection within a cell ID group (3hypothesis) 2^(nd) Step SSS Cell ID group detection (336 hypothesis)3^(rd) Step PBCH DMRS SSB index and Half frame index (Slot and frameboundary detection) 4^(th) Step PBCH Time information (80 ms, SFN, SSBindex, HF) RMSI CORESET/Search space configuration 5^(th) Step PDCCH andCell access information PDSCH RACH configuration

Although the SS and the PBCH block are composed of a PSS and an SSS,each which occupies one symbol and 127 subcarriers, and a PBCH whichspans 3 OFDM symbols and 240 subcarriers, respectively, one symbol isleft unused in the middle of the SSS, as illustrated in FIG. 19. Theperiod of the SS/PBCH block (SSB) may be configured by a network and thetime position at which the SSB may be transmitted is determined by asubcarrier spacing.

Polar coding is used for the PBCH. Unless the network configures the UEto assume different subcarrier spacings, the UE may assume band-specificsubcarrier spacings for the SSB.

A PBCH symbol carries a unique frequency-multiplexed DMRS. QPSKmodulation is used for the PBCH.

There are 1008 unique physical layer cell IDs.

$\begin{matrix}{N_{ID}^{cell} = {{3N_{ID}^{(1)}} + N_{ID}^{(2)}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

where N_(ID) ⁽¹⁾∈{0, 1, . . . , 335} and N_(ID) ⁽²⁾∈{0, 1, 2}.

A PSS sequence d_(PSS)(n) is defined as Equation 2 below.

$\begin{matrix}{{{d_{PSS}(n)} = {1 - {2{x(m)}}}}{m = {\left( {n + {43N_{ID}^{(2)}}} \right){mod}\; 127}}{0 \leq n < 127}{{x\left( {i + 7} \right)} = {{\left( {{x\left( {i + 4} \right)} + {x(i)}} \right){mod}\;{2\left\lbrack {{x(6)}\mspace{14mu}{x(5)}\mspace{14mu}{x(4)}\mspace{14mu}{x(3)}\mspace{14mu}{x(2)}\mspace{14mu}{x(1)}\mspace{14mu}{x(0)}} \right\rbrack}} = \left\lbrack {1\mspace{14mu} 1\mspace{14mu} 1\mspace{14mu} 0\mspace{14mu} 1\mspace{14mu} 1\mspace{14mu} 0} \right\rbrack}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

This sequence is mapped to a physical resource illustrated in FIG. 19.SSS sequence d_(SSS)(n) is defined as Equation 3.

$\begin{matrix}{{d_{SSS}(n)} = {\left\lbrack {1 - {2{x_{0}\left( {\left( {n + m_{0}} \right){mod}\; 127} \right)}}} \right\rbrack{\quad{{\left\lbrack {1 - {2{x_{1}\left( {\left( {n + m_{1}} \right){mod}\; 127} \right)}}} \right\rbrack m_{0}} = {{{15\left\lfloor \frac{N_{ID}^{(1)}}{112} \right\rfloor} + {5N_{ID}^{(2)}m_{1}}} = {{{N_{ID}^{(1)}\mspace{14mu}{mod}\; 1120} \leq n < {127{x_{0}\left( {i + 7} \right)}}} = {{\left( {{x_{0}\left( {i + 4} \right)} + {x_{0}(i)}} \right){mod}\; 2{x_{1}\left( {i + 7} \right)}} = {{\left( {{x_{1}\left( {i + 1} \right)} + {x_{1}(i)}} \right){mod}\;{2\left\lbrack {{x_{0}(6)}\mspace{14mu}{x_{0}(5)}\mspace{14mu}{x_{0}(4)}\mspace{14mu}{x_{0}(3)}\mspace{14mu}{x_{0}(2)}\mspace{14mu}{x_{0}(1)}\mspace{14mu}{x_{0}(0)}} \right\rbrack}} = {{\left\lbrack {0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 1} \right\rbrack\left\lbrack {{x_{1}(6)}\mspace{14mu}{x_{1}(5)}\mspace{14mu}{x_{1}(4)}\mspace{14mu}{x_{1}(3)}\mspace{14mu}{x_{1}(2)}\mspace{14mu}{x_{1}(1)}\mspace{14mu}{x_{0}(0)}} \right\rbrack} = {\quad\left\lbrack {0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 0\mspace{14mu} 1} \right\rbrack}}}}}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

This sequence is mapped to the physical resource illustrated in FIG. 19.

In the case of a half frame having the SSB, the first symbol index for acandidate SSB is determined according to a subcarrier spacing of the SSBas follows.

-   -   Case A—Subcarrier spacing of 15 kHz: The first symbol index of        the candidate SSB is {2, 8}+14*n. For carrier frequencies equal        to or greater than 3 GHz, n=0 and, for carrier frequencies        greater than 3 GHz and less than 6 GHz, n=0, 1, 2, 3.    -   Case B—Subcarrier spacing of 30 kHz: The first symbol index of        the candidate SSB is {4, 8, 16, 20}+28*n. For carrier        frequencies equal to or greater than 3 GHz, n=0 and, for carrier        frequencies greater than 3 GHz and less than 6 GHz, n=0, 1.    -   Case C—Subcarrier spacing of 30 kHz: The first symbol index of        the candidate SSB is {2, 8}+14*n. For carrier frequencies equal        to or greater than 3 GHz, n=0, 1 and, for carrier frequencies        greater than 3 GHz and less than 6 GHz, n=0, 1, 2, 3.    -   Case D—Subcarrier spacing of 120 kHz: The first symbol index of        the candidate SSB is {4, 8, 16, 20}+28*n. For carrier        frequencies greater than 6 GHz, n=0, 1, 2, 3, 5, 6, 7, 8, 10,        11, 12, 13, 15, 16, 17, 18.    -   Case E—Subcarrier spacing of 240 kHz: The first symbol index of        the candidate SSB is {8, 12, 16, 20, 32, 36, 40, 44}+56*n. For        carrier frequencies greater than 6 GHz, n=0, 1, 2, 3, 5, 6, 7,        8.

In a half frame, candidate SSBs are indexed in ascending order in orderof time f rom 0 to L−1. The UE should determine 2 least significant bits(LSBs) for L=4 of an SSB index per half frame or determine 3 LSBs forL>4, from one-to-one mapping with an index of a DM-RS sequencetransmitted through the PBCH. The UE should determine 3 most significantbits (MSBs) of the SSB index per half frame by a PBCH payload bitā_(Ā+5) ,ā_(Ā+6) ,ā_(Ā+7) for the case of L=4.

The UE may be configured by a higher layer parameterSSB-transmitted-SIB1, which is an SSB index for the UE that should notreceive another signal or channel of REs overlapping with REscorresponding to the SSB.

The UE may be configured by a higher layer parameter SSB-transmitted,which is an SSB index for the UE that should not receive another signalor channel overlapping with REs corresponding to the SSB, per servingcell. A configuration caused by SSB-transmitted may be prioritized overa configuration caused by SSB-transmitted-SIB1. The UE may be configuredby a higher layer parameter SSB-periodicityServingCell, which is aperiod of a half frame for reception of the SSB per serving cell, inevery serving cell. If the UE is not configured with the period of thehalf frame for reception of the SSB, the UE should assume the period ofthe half frame. The UE should assume that the period is the same withrespect to all SSBs of the serving cell.

FIG. 20 illustrates a method of acquiring timing information by a UE.

First, the UE may acquire 6-bit subframe number (SFN) informationthrough a master information block (MIB) received on a PBCH. Inaddition, the UE may acquire 4 bits of the SFN through a PBCH TB.

Second, the UE may obtain a 1-bit half frame indication as part of aPBCH payload. For a frequency below 3 GHz, the half frame indication isimplicitly signaled as part of a PBCH DMRS for Lmax=4.

Finally, the UE may acquire an SSB index by a DMRS sequence and the PBCHpayload. That is, 3 LSBs of an SS block index are obtained by the DMRSsequence within a 5 ms period. 3 MSBs of timing information areexplicitly signaled by the PBCH payload (for 6 GHz and above).

For initial cell selection, the UE may assume that a half frame havingthe SSB occurs at a period of two frames. Upon detection of the SSB, theUE determines that there is a control resource set for the Type0-PDCCHcommon search space when k_(SSB)≤23 for frequency range 1 (FR1) andk_(SSB)≤11 for frequency range 2 (FR2). The UE determines that there isno control resource set for the Type0-PDCCH common search space whenk_(SSB)>23 for FR1 and k_(SSB)>¹¹ for FR2.

For a serving cell without SSB transmission, the UE obtains time andfrequency synchronization of the serving cell based on SSB reception ina PCell or PSCell of a cell group for the serving cell.

System Information Acquisition

System information (SI) is divided into an MIB MasterInformationBlock)and multiple SIBs SystemInformationBlocks as follows.

-   -   MIB MasterInformationBlock is always transmitted on a BCH with a        periodicity of 80 ms and a repetition of 80 ms or less and        includes parameters needed to acquire SIB1        SystemInformationBlockType1 in a cell.    -   SIB1 SystemInformationBlockType1 is transmitted on a DL-SCH        periodically and repeatedly. SIB1 includes information about        availability and scheduling (e.g., periodicity and SI window        size) of other SIBs. SIB1 also indicates whether the other SIBs        are provided on a periodic broadcast basis or on a request        basis. If the other SIBs are provided on a request basis, SIB1        includes information needed by the UE to perform an SI request.    -   The SI other than SystemInformationBlockType1 is delivered        through SI (SystemInformation) messages transmitted on the        DL-SCH. Each SI message is transmitted within a time domain        window (SI window) that occurs periodically.    -   In case of a PSCell and an SCell, a RAN provides necessary SI        through dedicated signaling. Nevertheless, the UE should acquire        an MIB of the PSCell to obtain an SFN timing of a secondary cell        group (SCG) (which may be different from a master cell group        (MCG)). If relevant SI for the SCell is changed, the RAN        releases and adds the SCell. For the PSCell, the SI may be        changed only by reconfiguration through synchronization.

The UE acquires access stratum (AS) and a non-access stratum (NAS)information by applying an SI acquisition procedure. The procedure isapplied to UEs of RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED.

The UEs of RRC_IDLE and RRC_INACTIVE should have valid versions of (atleast) MasterinformationBlock, SystemInformationBlockType1, andSystemInformationBlockTypeX through SystemInformationBlockTypeY(depending on support of relevant RAT for UE control mobility).

The UE of RRC_CONNECTED should have valid versions of (at least)MasterInformationBlock, SystemInformationBlockType1, andSystemInformationBlockTypeX (depending on mobility support for relevantRAT).

The UE should store associated SI obtained from the currently campedcell/serving cell. The version of the SI acquired and stored by the UEis valid only for a certain time. The UE may use this stored version ofthe SI. For example, after cell reselection, the UE may use the storedversion of the SI upon returning back from out-of-coverage or afterindicating SI change.

Random Access

A random access procedure of the UE may be summarized as illustrated inTable 13 and FIG. 22.

TABLE 13 Type of Signals Operations/Information Acquired 1^(st) stepPRACH preamble Initial beam acquisition in UL Random election ofRA-preamble ID 2^(nd) Step Random Access Timing alignment informationResponse on DL-SCH RA-preamble ID Initial UL grant, Temporary C-RNTI3^(rd) Step UL transmission RRC connection request on UL-SCH UEidentifier 4^(th) Step Contention Temporary C-RNTI on PDCCH forResolution on DL initial access C-RNTI on PDCCH for UE in RRC_CONNECTED

First, the UE may transmit a physical random access channel (PRACH)preamble on UL as Msg1 of the random access procedure.

Two lengths of the random access preamble sequences are supported. Along sequence length of 839 is applied to subcarrier spacings of 1.25and 5 kHz and a short sequence length of 139 is applied to subcarrierspacings of 15, 30, 60, and 120 kHz. The long sequence supports anunrestricted set and restricted sets of Type A and Type B, whereas theshort sequence supports only the unrestricted set.

Multiple RACH preamble formats are defined as one or more RACH OFDMsymbols and different CP and guard times. A PRACH preamble configurationused is provided to the UE through SI.

If there is no response to Msg1, the UE may retransmit the PRACHpreamble through power ramping within a preset number of times. The UEcalculates PRACH transmit power for retransmission of the preamble basedon the most recent estimated path loss and a power ramp counter. Whenthe UE performs beam switching, the power ramping counter remainsunchanged.

An association between an SS block and an RACH resource is indicated tothe UE through the SI. FIG. 23 illustrates the concept of a threshold ofan SS block for RACH resource association.

The threshold of the SS block for the RACH resource association is basedon RSRP and network configurability. Transmission or retransmission ofthe RACH preamble is based on the SS block that satisfies the threshold.

When the UE receives a random access response on a DL-SCH, the DL-SCHmay provide timing alignment information, an RA-preamble ID, an initialUL grant, and a temporary C-RNTI.

Based on this information, the UE may perform UL transmission on aUL-SCH as Msg3 of the random access procedure. Msg3 may include an RRCconnection request and a UE ID.

In response to Msg3, the network may transmit Msg4, which may be treatedas a contention resolution message on DL. By receiving the Msg4, the UEmay enter an RRC connected state.

The detailed description of each step is as follows.

Before starting the physical random access procedure, Layer 1 shouldreceive a set of SSB indexes from a higher layer and provide an RSRPmeasurement set corresponding to the set of the SSB indexes to thehigher layer.

Before starting the physical random access procedure, Layer 1 shouldreceive the following information from the higher layer.

-   -   PRACH transmission parameter configuration (a PRACH preamble        format and time and frequency resources for PRACH transmission).    -   Parameters for determining a root sequence and a cyclic shift in        a PRACH preamble sequence set (an index of a logical root        sequence table, a cyclic shift N_(CS), and a set type        (unrestricted set, restricted set A, or restricted set B)).

From the perspective of a physical layer, an L1 random access procedureincludes transmission of a random access preamble Msg1 in a PRACH,transmission of a random access response (RAR) message with aPDCCH/PDSCH (Msg2), and, when applicable, transmission of a Msg3 PUSCHand transmission of the PDSCH for contention resolution.

If the random access procedure is initiated by “PDCCH order” for the UE,random access preamble transmission has the same subcarrier spacing asrandom access preamble transmission initiated by a higher layer.

If two UL carriers are configured for the UE with respect to a servingcell and the UE detects “PDCCH order”, the UE determines a UL carrierfor transmitting a corresponding random access preamble using a UL/SULindicator field value from the detected “PDCCH order”.

In association with the random access preamble transmission step, aphysical random access procedure is triggered according to a request ofPRACH transmission or the PDCCH order by the higher layer. A higherlayer configuration for PRACH transmission includes:

-   -   configuration for PRACH transmission, and    -   a preamble index, a preamble subcarrier spacing P_(PRACHtarget),        a corresponding RA-RNTI, and a PRACH resource.

The preamble is transmitted using a PRACH format selected with transmitpower P_(PRACH,b,f,c)(i) on an indicated PRACH resource.

The UE is provided with a plurality of SSBs associated with one PRACHoccasion by the value of a higher layer parameter SSB-perRACH-Occasion.If the value of SSB-perRACH-Occasion is less than 1, one SSB is mappedto SSB-perRACH-Occasion, which is one/consecutive PRACH occasions. TheUE is provided with a plurality of preambles per SSB by the value of ahigher layer parameter cb-preamblePerSSB and determines a total numberof preambles per SSB per PRACH occasion as the product of the values ofSSB-perRACH-Occasion and cb-preamblePerSSB.

SSB indexes are mapped to PRACH occasions in the following order.

-   -   First, order in which preamble indexes increase in a single        PRACH occasion.    -   Second, order in which frequency resource indexes for frequency        multiplexed PRACH occasions increase.    -   Third, order in which time indexes for time multiplexed PRACH        occasions in a PRACH slot increase.    -   Fourth, order in which indexes for a PRACH slot increase.

A period starting from frame 0, for mapping SSBs to PRACH occasions, isthe smallest period among PRACH configuration periods such as {1, 2, 4},greater than or equal to ┌N_(Tx) ^(SSB)/N_(PRACHperiod) ^(SSB)┐. In thiscase, the UE obtains N_(Tx) ^(SSB) from the higher layer parameterSSB-transmitted-SIB1 and N_(PRACHberiod) ^(SSB) is the number of SSBscapable of being mapped to one PRACH configuration period.

If a random access procedure is initialized by the PDCCH order, the UEshould transmit a PRACH in the first available PRACH occasion, which istime between the last symbol of PDCCH order reception and the firstsymbol of PRACH transmission, equal to or greater thanN_(T,2)+Δ_(BWPSwitching)+Δ_(Delay) msec, at the request of the higherlayer. N_(T,2) is a time duration of N₂ symbols corresponding to a PUSCHpreparation time for PUSCH processing capability 1 and Δ_(BWPSwitching)is a preset value, and Δ_(Delay)>0. In response to PRACH transmission,the UE attempts to detect a PDCCH corresponding to an RA-RNTI during awindow controlled by the higher layer.

The window is started in the first symbol of an initial control resourceset. The UE is configured for a Type1-PDCCH common search space which isa symbol ┌(Δ·N_(slot) ^(subframeμ)·B_(symb) ^(slot))/T_(sf)┌ after thelast symbol of preamble sequence transmission.

The length of the window indicated as the number of slots, based on asubcarrier spacing for a Type0-PDCCH common search space, is provided bya higher layer parameter rar-WindowLength.

If the UE detects a PDCCH corresponding to an RA-RNTI and acorresponding PDSCH including a DL-SCH TB in the window, the UE deliversa TB to the higher layer. The higher layer parses a TB for a randomaccess preamble identity (RAPID) related to PRACH transmission. If thehigher layer identifies the RAPID in RAR message(s) of the DL-SCH TB,the higher layer indicates a UL grant to a physical layer. This isreferred to as a random access response (RAR) UL grant in the physicallayer. If the higher layer does not identify the RAPID associated withPRACH transmission, the higher layer may instruct the physical layer totransmit the PRACH. A minimum time between the last symbol of PDSCHreception and the first symbol of PRACH transmission is equal toN_(T,1)+Δ_(new)+0.5 msec. In this case, N_(T,1) denotes a time durationof N₁ symbols corresponding to a PDSCH reception time for PDSCHprocessing capability 1 when an additional PDSCH DM-RS is configured.

The UE should receive a PDSCH including a DL-SCH TB having the sameDM-RS antenna port quasi co-location attribute as the detected SSB orreceived CSI and receive a PDCCH of a corresponding RA-RNTI. When the UEattempts to detect the PDCCH corresponding to the RA-RNTI in response toPRACH transmission initiated by the PDCCH order, the UE assumes that thePDCCH and the PDCCH order have the same DM-RS antenna port quasico-location attribute.

An RAR UL grant schedules PUSCH transmission from the UE (Msg3 PUSCH).The contents of an RAR UL grant that begin with the MSB and end with theLSB are shown in Table 14. Table 14 shows the size of an RAR grantcontent field.

TABLE 14 RAR grant field Number of bits Frequency hopping flag 1 Msg3PUSCH frequency 12 resource allocation Msg3 PUSCH time 4 resourceallocation MCS 4 TPC command for Msg3 PUSCH 3 CSI request 1 Reservedbits 3

Msg3 PUSCH frequency resource allocation is for UL resource allocationtype 1. For frequency hopping, the first bit, two bits, or N_(UL,hop)bits of an Msg3 PUSCH frequency resource allocation field are used ashopping information bits as shown in Table 14, based on indication of afrequency hopping flag field.

An MCS is determined from the first 16 indexes of an MCS index tableapplicable to a PUSCH.

A TPC command δ_(msg2,b,f,c) is used to set the power of the Msg3 PUSCHand is interpreted according to Table 15. Table 15 shows the TPC commandfor the Msg3 PUSCH.

TABLE 15 TPC Command Value (in dB) 0 −6 1 −4 2 −2 3 0 4 2 5 4 6 6 7 8

In a non-contention-based random access procedure, a CSI request fieldis interpreted to determine if aperiodic CSI reporting is included incorresponding PUSCH transmission. In a contention-based random accessprocedure, the CSI request field is reserved.

Unless the UE configures a subcarrier spacing, the UE receives asubsequent PDSCH using the same subcarrier spacing as PDSCH receptionproviding an RAR message.

If the UE fails to detect a PDCCH in a window using a correspondingRA-RNTI and a corresponding DL-SCH TB, the UE performs a RAR receptionfailure procedure.

For example, the UE may perform power ramping for retransmission of arandom access preamble based on the power ramping counter. However, thepower ramping counter remains unchanged when the UE performs beamswitching in PRACH retransmission as illustrated in FIG. 16.

In FIG. 24, when the UE retransmits a random access preamble for thesame beam, the UE may increase the power ramping counter by one.However, even if a beam is changed, the power ramp counter is notchanged.

In relation to Msg3 PUSCH transmission, a higher layer parameter msg3-tpindicates whether the UE should apply transform precoding to Msg3 PUSCHtransmission. When the UE applies transform precoding to Msg3 PUSCHtransmission having frequency hopping, a frequency offset for the secondhop is given in Table 16. Table 16 shows the frequency offset for thesecond hop for Msg3 PUSCH transmission having frequency hopping.

TABLE 16 Number of PRBs in initial active Value of N_(UL, hop) Frequencyoffset for UL BWP Hopping Bits 2^(nd) hop N_(BWP) ^(size) < 50 0 N_(BWP)^(size)/2 1 N_(BWP) ^(size)/4 00 N_(BWP) ^(size)/2 N_(BWP) ^(size) ≥ 5001 N_(BWP) ^(size)/4 10 −N_(BWP) ^(size)/4  11 Reserved

A subcarrier spacing for Msg3 PUSCH transmission is provided by a higherlayer parameter msg3-scs. The UE should transmit the PRACH and Msg3PUSCH on the same UL carrier of the same serving cell. A UL BWP for Msg3PUSCH transmission is indicated by SystemInformationBlockType1.

If a PDSCH and a PUSCH have the same subcarrier spacing, a minimum timebetween the last symbol of PDSCH reception carrying a RAR to the UE andthe first symbol of corresponding Msg3 PUSCH transmission scheduled bythe RAR of the PDSCH is equal to N_(T,1)+N_(T,2)+N_(TA,max)+0.5 msec.N_(T,1) is the time interval of N₂ symbols corresponding to a PDSCHreception time for PDSCH processing capability 1 when an additionalPDSCH DM-RS is configured. N₁₂ is a time interval of symbolscorresponding to a PUSCH preparation time for PUSCH processingcapability 1, and N_(TA,max) is a maximum timing adjustment value thatmay be provided in a TA command field of the RAR. In response to Msg3PUSCH transmission when a C-RNTI is not provided to the UE, the UEattempts to detect a PDCCH with a TC-RNTI scheduling a PDSCH including aUE contention-resolution ID. Upon receiving a PDSCH through the UEcontention resolution ID, the UE transmits HARQ-ACK information on thePUCCH. A minimum time between the last symbol of PDSCH reception and thefirst symbol of corresponding HARQ-ACK transmission is equal toN_(T,1)+0.5 msec. In this case, N_(T,1) is a time duration of N₁ symbolscorresponding to a PDSCH reception time for PDSCH processing capability1 when an additional PDSCH DM-RS is configured.

Channel Coding Scheme

A channel coding scheme for an embodiment mainly includes (1) alow-density parity check (LDPC) coding scheme for data, and (2) othercoding schemes such as polar coding and iterative coding/simplexcoding/Reed-Muller coding for control information.

Specifically, the network/UE may perform LDPC coding for the PDSCH/PUSCHby supporting two base graphs (BGs). BG1 has a mother code rate of 1/3and BG2 has a mother code rate of 1/5.

For coding of control information, iterative coding/simplexcoding/Reed-Muller coding may be supported. If the control informationhas a length longer than 11 bits, the polar coding scheme may be used.For DL, the size of the mother code may be 512 and, for UL, the size ofthe mother code may be 1024. Table 17 summarizes the coding scheme of ULcontrol information.

TABLE 17 Uplink Control Information size including CRC, if presentChannel code 1 Repetition code 2 Simplex code 3-11 Reed Muller code >11 Polar code

As mentioned above, the polar coding scheme may be used for the PBCH.This coding scheme may be the same as in the PDCCH.

An LDPC coding structure is described in detail.

An LDPC code is an (n, k) linear block code defined as a null space of(n, k)×a sparse parity-check matrix H.

$\begin{matrix}{{{Hx}^{T} = 0}{{Hx}^{T} = {{\begin{bmatrix}1 & 1 & 1 & 0 & 0 \\1 & 0 & 0 & 1 & 1 \\1 & 1 & 0 & 0 & 0 \\0 & 1 & 1 & 1 & 0\end{bmatrix}\begin{bmatrix}x_{1} \\x_{2} \\x_{3} \\x_{4} \\x_{5}\end{bmatrix}} = \begin{bmatrix}0 \\0 \\0 \\0\end{bmatrix}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

The parity-check matrix is represented by a prototype graph asillustrated in FIG. 25.

In one embodiment, a quasi-cyclic (QC) LDPC code is used. In thisembodiment, the parity-check matrix is an m×n array of a Z×Z cyclicpermutation matrix. Complexity may be reduced and highly parallelizableencoding and decoding may be obtained using this QC LDPC.

FIG. 26 illustrates an example of a parity-check matrix based on a 4×4cyclic permutation matrix.

In FIG. 26, H is represented by a shift value (cyclic matrix) and 0(zero matrix) instead of Pi.

FIG. 27 illustrates an encoder structure for a polar code. Specifically,FIG. 27(a) illustrates a basic module of the polar code and FIG. 27(b)illustrates a basic matrix.

The polar code is known in the art as a code capable of obtainingchannel capacity in a binary input discrete memoryless channel (B-DMC).That is, channel capacity may be obtained when the size N of a codeblock is increased to infinity. An encoder of the polar code performschannel combining and channel splitting as illustrated in FIG. 28.

UE States and State Transition

FIG. 29 illustrates a UE RRC state machine and state transition. The UEhas only one RRC state at a time.

FIG. 30 illustrates a UE state machine, state transition, and a mobilityprocedure supported between an NR/NGC and an E-UTRAN/EPC.

The RRC state indicates whether an RRC layer of the UE is logicallyconnected to an RRC layer of the NG RAN.

When an RRC connection is established, the UE is in RRC_CONNECTED stateor RRC_INACTIVE state. Otherwise, that is, if no RRC connection isestablished, the UE is in RRC_IDLE state.

When the UE is in RRC_CONNECTED state or RRC_INACTIVE state, the UE hasan RRC connection, so that the NG RAN may recognize the presence of theUE in a cell unit. Therefore, it is possible to effectively control theUE. Meanwhile, when the UE is in RRC_IDLE state, the UE may not berecognized by the NG RAN and is managed by a core network in a trackingarea unit, which is a unit of a larger area than a cell. That is, onlythe presence of the UE is recognized in a wide area unit for the UE inRRC_IDLE state. In order to receive general mobile communicationservices such as voice or data, it is necessary to switch toRRC_CONNECTED state.

When the user first turns on the UE, the UE first searches for anappropriate cell and then maintains RRC_IDLE state in the cell. Onlywhen it is necessary to establish an RRC connection, does the UE inRRC_IDLE state establish an RRC connection with the NG RAN through anRRC connection procedure and then transition to RRC_CONNECTED state orRRC_INACTIVE state. When the UE in RRC_IDLE needs to establish an RRCconnection includes various cases in which, for example, a UL datatransmission is required due to a telephone attempt by a user or aresponse message is transmitted in response to a paging message receivedfrom the NG RAN.

RRC_IDLE state and RRC_INACTIVE state have the followingcharacteristics.

(1) RRC_IDLE:

-   -   UE-specific discontinuous reception (DRX) may be configured by a        higher layer;    -   UE control mobility based on network configuration;    -   UE:    -   monitors a paging channel;    -   performs adjacent cell measurement and cell (reselection); and    -   acquire SI.

(2) RRC_INACTIVE:

-   -   UE-specific DRX may be configured by the higher layer or RRC        layer;    -   UE control mobility based on network configuration;    -   The UE stores an access stratum (AS) context;    -   UE:    -   monitors the paging channel;    -   performs adjacent cell measurement and cell (reselection);    -   performs RAN-based notification area update when the UE moves        out of a RAN-based notification area; and    -   acquires SI.

(3) RRC_CONNECTED:

-   -   The UE stores an AS context;    -   Unicast data with the UE is transmitted;    -   In a lower layer, the UE may be configured with UE-specific DRX;    -   For the UE supporting CA, one or more SCells aggregated with an        SpCell are used for extended bandwidth;    -   For the UE supporting DC, one SCG aggregated with an MCG is used        for extended bandwidth;    -   Network control mobility to an E-UTRAN/from the E-UTRAN in-NR;    -   UE:    -   monitors a paging channel;    -   confirms whether data is reserved by monitoring a control        channel associated with a shared data channel;    -   provides channel quality and feedback information;    -   performs adjacent cell measurement and measurement reporting;        and    -   acquires SI.

RRC_IDLE State and RRC_INACTIVE State

A UE procedure related to RRC_IDLE state and RRC_INACTIVE state issummarized as shown in Table 18.

TABLE 18 UE procedure 1^(st) step a public land mobile network (PLMN)selection when a UE is switched on 2^(nd) Step cell (re)selection forsearching a suitable cell 3^(rd) Step tune to its control channel(camping on the cell) 4^(th) Step Location registration and a RAN-basedNotification Area (RNA) update

PLMN selection, cell reselection procedure, and location registrationare common to both RRC_IDLE state and RRC_INACTIVE state.

When the UE is powered on, a PLMN is selected by a non-access stratum(NAS). For the selected PLMN, associated radio access technology (RAT)may be configured. If possible, the NAS should provide an equivalentPLMN list that the AS will use for cell selection and cell reselection.

Through cell selection, the UE searches for a suitable cell of theselected PLMN and selects the cell in order to provide availableservices. Additionally, the UE should tune to a control channel thereof.This selection is called “camping on the cell”.

While the UE is in RRC_IDLE state, three levels of service are provided:

-   -   limited services (emergency calls, ETWS and CMAS in an        acceptable cell);    -   normal services (for public use in a suitable cell);    -   operator services (allowed only for operators in a reserved        cell)    -   The following two levels of services are provided while the UE        is in RRC_INACTIVE state.    -   normal services (for public use in a suitable cell);    -   operator services (allowed only for operators in a reserved        cell).

If necessary, the UE registers presence thereof in a tracking area ofthe selected cell through a NAS registration procedure and a PLMNselected as a result of successful location registration becomes aregistered PLMN.

If the UE finds a suitable cell according to a cell reselectioncriterion, the UE reselects the cell and camps on the cell. If a newcell does not belong to at least one tracking area in which the UE isregistered, location registration is performed. In RRC_INACTIVE state,if the new cell does not belong to a configured RNA, an RNA updateprocedure is performed.

If necessary, the UE should search for a PLMN having a high priority atregular time intervals and search for a suitable cell when the NASselects another PLMN.

If the UE loses coverage of the registered PLMN, a new PLMN may beautomatically selected (automatic mode) or an indication indicatingwhich PLMN is available may be given to the UE so as to make manualselection (manual mode).

Registration is not performed by a UE capable of providing only servicesthat do not require registration.

There are four purposes of camping on cells of RRC_IDLE state andRRC_INACTIVE state.

a) The UE may receive system information from the PLMN.

b) When registration is performed and when the UE tries to establish anRRC connection, this may be performed by first accessing a network via acontrol channel of a camped cell.

c) Upon receiving a call to a registered UE, the PLMN is aware of (inmost cases) a set of tracking areas (RCR_IDLE state) or RNA(RCC_INACTIVE state) on which the UE is camped. A “paging” message maybe sent to the UE on control channels of all cells of the area set. TheUE may receive a paging message and respond to the paging message.

Three processes that are distinguished from RRC_IDLE state andRRC_INACTIVE state will now be described.

First, a PLMN selection procedure is described.

In the UE, an AS should report, to a NAS, available PLMNs at the requestof the NAS or autonomously.

In the PLMN selection procedure, a specific PLMN may be selectedautomatically or manually based on a priority-based PLMN ID list. EachPLMN in the PLMN ID list is identified by a ‘PLMN ID’. In systeminformation of a broadcast channel, the UE may receive one or more ‘PLMNIDs’ in a given cell. A result of PLMN selection performed by the NAS isan ID of the selected PLMN.

The UE should scan all RF channels in an NR band according tocapabilities thereof to find the available PLMNs. On each carrier, theUE should search for the strongest cell and read SI of the cell to findout which PLMN(s) belong to the cell. If the UE can read one or severalPLMN IDs in the strongest cell and the following high quality criteriaare satisfied, each of the found PLMNs should be reported to the NAS asa high quality PLMN (without RSRP value).

For an NR cell, a measured RSRP value should be −110 dBm or more.

Found PLMNs that do not meet the high quality criteria but have IDscapable of being read by the UE are reported to the NAS along with anRSRP value. A quality measurement value reported to the NAS by the UEshould be the same with respect to each PLMN found in one cell.

PLMN search may be stopped at the request of the NAS. The UE mayoptimize PLMN search using stored information, for example, informationabout a carrier frequency and optionally information about a cellparameter from a previously received measurement control informationelement.

If the UE selects a PLMN, the cell selection procedure should beperformed to select an appropriate cell of the PLMN on which the UE isto camp.

Next, cell selection and cell reselection will be described.

The UE should perform measurement for the purpose of cell selection andreselection.

The NAS may control RAT for which cell selection should be performed,for example, by indicating RAT associated with the selected PLMN andmaintaining a list of forbidden registration area(s) and a list ofequivalent PLMNs. The UE should select an appropriate cell based onRRC_IDLE state measurement and cell selection criteria.

To facilitate a cell selection process, the UE may use storedinformation about several RATs.

Upon camping on a cell, the UE should regularly search for a better cellaccording to the cell reselection criteria. If a better cell is found,the cell is selected. Change in a cell may mean change in RAT. Ifreceived SI related to the NAS is changed due to cell selection andreselection, the UE informs the NAS of change in the SI.

For a normal service, the UE should camp on a suitable cell and tune tocontrol channel(s) of the cell so that the UE may perform the followingoperations:

-   -   receive SI from the PLMN;    -   receive registration area information such as tracking area        information from the PLMN; and    -   receive information about another AS and NAS;    -   If registration is performed, the UE:    -   receives paging and notification messages from the PLMN; and    -   start transmission in connected mode

For cell selection, the measurement quantity of a cell depends on UEimplementation.

For cell reselection in a multi-beam operation, the UE derivesmeasurement quantity of a cell as follows amongst beams corresponding tothe same cell based on an SSB, using the maximum number of beams to beconsidered and a threshold provided through SystemInformationBlockTypeX.

-   -   If a maximum value of beam measurement quantities is below the        threshold:    -   the UE derives a cell measurement quantity as the highest beam        measurement quantity value;    -   otherwise,    -   the UE derives a cell measurement quantity as the linear average        of power values up to the maximum number of the highest        measurement quantity values above the threshold.

Cell selection is performed by one of the following two procedures.

a) Initial cell selection (without prior knowledge of which RF channelis an NR carrier);

1. The UE should scan all RF channels in an NR band according tocapabilities thereof to find an appropriate cell.

2. On each carrier frequency, the UE needs to search for the strongestcell.

3. Once a suitable cell is found, the UE should select this cell.

b) The UE selects a cell using stored information.

1. This procedure requires stored information of a carrier frequency andoptionally information about a cell parameter from a previously receivedmeasurement control information element or a previously detected cell.

2. If the UE finds a suitable cell, the UE should select this cell.

3. If no suitable cell is found, the initial cell selection procedureshould be started.

Next, cell reservation and access restriction procedures will bedescribed.

There are two mechanisms which allow an operator to impose cellreservation or access restriction. The first mechanism uses indicationof cell status and special reservations for control of cell selectionand reselection procedures. The second mechanism, referred to as unifiedaccess control, should allow preventing selected access classes oraccess IDs from sending initial access messages for load controlreasons.

Cell status and cell reservation are indicated in anMasterinformationBlock or SystemInformationBlockType1 (SIB1) message bymeans of three fields below:

-   -   cellBarred (IE type: “barred” or “not barred”)

This field is indicated through the MasterinformationBlock message. Inthe case of multiple PLMNs indicated in SIB1, this field is common toall PLMNs.

-   -   cellReservedForOperatorUse (IE type: “reserved” or “not        reserved”)

This field is indicated through the SystemInformationBlockType1 message.In the case of multiple PLMNs indicated in SIB1, this field is specifiedper PLMN.

-   -   cellReservedForOtherUse (IE type: “reserved” or “not reserved”)

This field is indicated through the SystemInformationBlockType1 message.In the case of multiple PLMNs indicated in SIB1, this field is common toall PLMNs.

If a cell status is indicated as “not barred” and “not reserved” andindicated as “not reserved” for other use,

-   -   all UEs should treat this cell as a candidate cell during cell        selection and cell reselection procedures.

If the cell status is indicated as “reserved” for other use,

-   -   a UE should treat this cell as a cell status of “barred”.

If the cell status is indicated as “not barred” and “reserved” foroperator use for a PLMN and as “not reserved” for other use,

-   -   a UE allocated to access identity 11 or 15 operating in an        HPLMN/EHPLMN should treat this cell as a candidate cell during        the cell selection and reselection procedures if a        cellReservedForOperatorUse field for the PLMN is set to as        “reserved”, and    -   a UE allocated to an access identity in the range of 12 to 14        should behave as if a cell status is “barred” if the cell is        “reserved for operator use” for a registered PLMN or a selected        PLMN.

If the cell status “barred” is indicated or treated as if the cellstatus is “barred”,

-   -   The UE is not permitted to select/reselect this cell, not even        in an emergency call.    -   The UE should select another cell according to the following        rule:    -   If the cell status is treated as if the cell status is “barred”        because MasterInformationBlock or SystemInformationBlockType1 is        not obtainable:    -   the UE may exclude the barred cell as a candidate for cell        selection/reselection for up to 300 seconds.    -   If selection criteria are fulfilled, the UE may select another        cell in the same frequency.    -   Otherwise.    -   if an intraFreqReselection field of the MasterinformationBlock        message is set to “allowed” and the reselection criteria are        fulfilled, the UE may select another cell in the same frequency.    -   The UE should exclude the barred cell as a candidate for cell        selection/reselection for 300 seconds.    -   If the intraFreqReselection field of the MasterinformationBlock        message is set to “not allowed”, the UE should not reselect a        cell in the same frequency as the barred cell.    -   The UE should exclude the barred cell and a cell in the same        frequency as a candidate for cell selection/reselection for 300        seconds.

Cell selection of another cell may also include a change in RAT.

Information about cell access restrictions associated with accesscategories and identities is broadcast as SI.

The UE should ignore access category and identity related cell accessrestrictions for cell reselection. A change in the indicated accessrestriction should not trigger cell reselection by the UE.

The UE should consider access category and identity related cell accessrestrictions for NAS initiated access attempts and RAN-basednotification area update (RNAU).

Next, tracking area registration and RAN area registration procedureswill be described.

In the UE, an AS should report tracking area information to a NAS.

If the UE reads one or more PLMN identities in a current cell, the UEshould report the found PLMN identities that make the cell suitable inthe tracking area information to the NAS.

The UE transmits the RNAU periodically or when the UE selects a cellthat does not belong to a configured RNA.

Next, mobility in RRC_IDLE and RRC_INACTIVE will be described in moredetail.

PLMN selection in NR is based on 3GPP PLMN selection rules. Cellselection is required upon transition from RM-DEREGISTERED toRM-REGISTERED, from CM-IDLE to CM-CONNECTED, or from CM-CONNECTED toCM-IDLE, based on the following rules.

-   -   A UE NAS layer identifies a selected PLMN and equivalent PLMNs        of the selected PLMN.    -   The UE scans NR frequency bands and identifies the strongest        cell for each carrier frequency. The UE reads broadcast SI of        the cell to identify a PLMN.    -   The UE may sequentially scan each carrier (“initial cell        selection”) or use stored information to shorten search (“stored        information cell selection”).

The UE tries to identify a suitable cell; if no suitable cell can beidentified, the UE tries to identify an acceptable cell. If a suitablecell is found or only an acceptable cell is found, the UE starts to campon the corresponding cell and begins a cell reselection procedure.

-   -   The suitable cell is a cell in which measured cell attributes        satisfy cell selection criteria. A cell PLMN is a selected PLMN,        or a registered or equivalent PLMN; the cell is not barred or        reserved, and the cell is not part of a tracking area which is        on the list of “forbidden tracking areas for roaming”.    -   The acceptable cell is a cell, measured cell attributes of which        satisfy the cell selection criteria, and the cell is not barred;

Transition to RRC_IDLE:

Upon transition from RRC_CONNECTED to RRC_IDLE, the UE camps on the lastcell/any cell of a cell set, which has been in RRC_CONNECTED, accordingto a frequency allocated by RRC in a cell/state transition message.

Recovery from out-of-coverage:

The UE should attempt to find a suitable cell in the manner describedfor the stored information or initial cell selection. If no suitablecell is found in any frequency or RAT, the UE should attempt to find anacceptable cell.

In a multi-beam operation, cell quality is derived amongst beamscorresponding to the same cell.

The UE of RRC_IDLE performs cell reselection. The principle of theprocedure is as follows.

-   -   The UE measures attributes of serving and neighboring cells to        enable a reselection process    -   For search and measurement of inter-frequency neighboring cells,        only carrier frequencies need to be indicated.    -   Cell reselection identifies a cell that the UE should camp on.        Cell reselection is based on cell reselection criteria which        involves measurement of serving and neighboring cells:    -   Intra-frequency reselection is based on ranking of cells;    -   Inter-frequency reselection is based on absolute priorities at        which the UE attempts to camp on the highest priority frequency        available;    -   An NCL may be provided by the serving cell to handle a specific        case for intra-frequency and inter-frequency neighboring cells.    -   A blacklist may be provided to prevent the UE from reselecting        specific intra-frequency and inter-frequency neighboring cells.    -   Cell reselection may be speed dependent;    -   Service specific prioritization.

In multi-beam operation, cell quality is derived amongst beamscorresponding to the same cell.

RRC_INACTIVE is a state in which the UE remains CM-CONNECTED state andmay move within an area configured by an NG-RAN (an RNA) withoutnotifying the NG-RAN. In RRC_INACTIVE, the last serving gNB nodemaintains UE context and UE associated NG connection with a serving AMFand UPF.

If the last serving gNB receives DL data from the UPF or a DL signalfrom the AMF while the UE is in RRC_INACTIVE, the UE pages in a cellcorresponding to the RNA and may transmit Xn application protocol (XnAP)RAN paging to a neighboring gNB if the RNA includes cells of neighboringgNB(s).

The AMF provides RRC inactive assistance information to the NG-RAN nodeto assist the NG-RAN node in determining whether the UE may transitionto RRC_INACTIVE. The RRC inactive assistance information includes aregistration area configured for the UE, UE-specific DRX, a periodicregistration update timer, an indication if the UE is configured inmobile initiated connection only (MICO) mode by the AMF, and a UE IDindex value. The UE registration area is considered by the NG-RAN nodewhen configuring the RAN based notification area. The UE-specific DRXand the UE ID index value are used by the NG-RAN node for RAN paging.The periodic registration update timer is considered to configure aperiodic RAN notification area update timer in the NG-RAN node.

In transitioning to RRC_INACTIVE, the NG-RAN node may configure the UEwith a periodic RNA update timer value.

If the UE accesses a gNB other than the last serving gNB, a receivinggNB may trigger an XnAP retrieve UE context procedure to obtain a UEcontext from the last serving gNB and trigger a data delivery procedureincluding tunnel information for potential recovery of data from thelast serving gNB. Upon performing successful context retrieval, thereceiving gNB becomes a serving gNB and further triggers an NGapplication protocol (NGAP) path switch request procedure. After thepath switch procedure, the serving gNB triggers release of the UEcontext in the last serving gNB by the XnAP UE context releaseprocedure.

If the UE accesses a gNB other than the last serving gNB and thereceiving gNB fails to find a valid UE context, the gNB performsestablishment of a new RRC connection instead of resumption of aprevious RRC connection.

The UE in RRC_INACTIVE state is required to initiate an RNA updateprocedure when the UE moves out of the configured RNA. Upon receiving anRNA update request from the UE, the receiving gNB may decide to send theUE back to the RRC_INACTIVE state, move the UE to the RRC_CONNECTEDstate, or transition the UE to RRC_IDLE.

The UE in RRC_INACTIVE performs cell reselection. The principle of theprocedure is the same as for RRC_IDLE state.

Discontinuous Reception (DRX)

A UE procedure related to DRX may be summarized as shown in Table 19.

TABLE 19 Type of signals UE procedure 1^(st) step RRC signalling ReceiveDRX configuration information (MAC- CellGroupConfig) 2^(nd) Step MAC CEReceive DRX command ((Long) DRX command MAC CE) 3^(rd) Step — Monitor aPDCCH during an on-duration of a DRX cycle

FIG. 31 illustrates a DRX cycle.

The UE uses DRX in RRC_IDLE and RRC_INACTIVE states to reduce powerconsumption.

If DRX is configured, the UE performs a DRX operation according to DRXconfiguration information.

The UE acting as DRX repeatedly turns on and off a receive operation.

For example, if DRX is configured, the UE attempts to receive a PDCCH,which is a DL channel, only for a predetermined time duration and doesnot attempt to receive the PDCCH for the other time duration. In thiscase, a duration during which the UE should attempt to receive the PDCCHis called an on-duration and this on-duration is defined once every DRXcycle.

The UE may receive DRX configuration information from the gNB throughRRC signaling and operate as DRX through reception of a (long) DRXcommand MAC CE.

The DRX configuration information may be included inMAC-CellGroupConfig.

The information element (IE) MAC-CellGroupConfig is used to configureMAC parameters for a cell group including DRX.

Table 20 and Table 21 are examples of the IE MAC-CellGroupConfig.

TABLE 20 -- ASN1START -- TAG-MAC-CELL-GROUP-CONFIG-STARTMAC-CellGroupConfig ::=  SEQUENCE {  drx-Config  SetupRelease {DRX-Config }  schedulingRequestConfig  SchedulingRequestConfig bsr-Config  BSR-Config  tag-Config  TAG-Config  phr-Config SetupRelease { PHR-Config }  skipUplinkTxDynamic   BOOLEAN,  cs-RNTI  SetupRelease { RNTI-Value } } DRX-Config ::=  SEQUENCE { drx-onDurationTimer   CHOICE {   subMilliSeconds INTEGER (1..31),  milliSeconds ENUMERATED {  ms1, ms2, ms3, ms4, ms5, ms6, ms8, ms10,ms20,    ms30, ms40, ms50, ms60, ms80, ms100,    ms200, ms300, ms400,ms500, ms600,    ms800, ms1000, ms1200, ms1600, spare9,    spare8,spare7, spare6, spare5, spare4, spare3,    spare2, spare1}   }, drx-InactivityTimer  ENUMERATED {  ms0, ms1, ms2, ms3, ms4, ms5, ms6,ms8, ms10,    ms20, ms30, ms40, ms50, ms60, ms80,    ms100, ms200,ms300, ms500, ms750,    ms1280, ms1920, ms2560, spare9, spare8,   spare7, spare6, spare5, spare4, spare3, spare2,    spare1}, drx-HARQ-RTT-TimerDL   INTEGER (0..56),  drx-HARQ-RTT-TimerUL   INTEGER(0..56),  drx-RetransmissionTimerDL   ENUMERATED {   sl0, sl1, sl2, sl4,sl6, sl8, sl16, sl24, sl33, sl40,    sl64, sl80, sl96, sl112, sl128,sl160, sl320,    spare15, spare14, spare13, spare12, spare11,   spare10, spare9, spare8, spare7, spare6,    spare5, spare4, spare3,spare2, spare1},  drx-RetransmissionTimerUL   ENUMERATED {  sl0, sl1,sl2, sl4, sl6, sl8, sl16, sl24, sl33, sl40, sl64,    sl80, sl96, sl112,sl128, sl160, sl320, spare15,    spare14, spare13, spare12, spare11,spare10,    spare9, spare8, spare7, spare6, spare5, spare4,    spare3,spare2, spare1 },  drx-LongCycleStartOffset CHOICE {   ms10 INTEGER(0..9),   ms20  INTEGER(0..19),   ms32  INTEGER(0..31),   ms40 INTEGER(0..39),   ms60  INTEGER(0..59),   ms64  INTEGER(0..63),   ms70 INTEGER(0..69),   ms80  INTEGER(0..79),   ms128  INTEGER(0..127),  ms160  INTEGER(0..159),   ms256  INTEGER(0..255),   ms320 INTEGER(0..319),   ms512  INTEGER(0..511),   ms640  INTEGER(0..639),  ms1024  INTEGER(0..1023),   ms1280  INTEGER(0..1279),   ms2048 INTEGER(0..2047),   ms2560  INTEGER(0..2559),   ms5120 INTEGER(0..5119),   ms10240  INTEGER(0..10239)  },  shortDRX  SEQUENCE{   drx-ShortCycle   ENUMERATED {    ms2, ms3, ms4, ms5, ms6, ms7, ms8,ms10,     ms14, ms16, ms20, ms30, ms32, ms35,     ms40, ms64, ms80,ms128, ms160,     ms256, ms320, ms512, ms640,     spare9,spare8, spare7,spare6, spare5,     spare4, spare3, spare2, spare1 },  drx-ShortCycleTimer    INTEGER (1.16)  } OPTIONAL,      -- Need R drx-SlotOffset  INTEGER (0..31) }

TABLE 21 MAC-CellGroupConfig field descriptions drx-Config Used toconfigure DRX. drx-HARQ-RTT-TimerDL Value in number of symbols.drx-HARQ-RTT-TimerUL Value in number of symbols. drx-InactivityTimerValue in multiple integers of 1 ms. ms0 corresponds to 0, ms1corresponds to 1 ms, ms2 corresponds to 2 ms, and so on.drx-onDurationTimer Value in multiples of 1/32 ms (subMilliSeconds) orin ms (milliSecond). For the latter, ms1 corresponds to 1 ms, ms2corresponds to 2 ms, and so on. drx-LongCycleStartOffset drx-LongCyclein ms and drx-StartOffset in multiples of 1 ms.drx-RetransmissionTimerDL Value in number of slot lengths, sl1corresponds to 1 slot, sl2 corresponds to 2 slots, and so on.drx-RetransmissionTimerUL Value in number of slot lengths, sl1corresponds to 1 slot, sl2 corresponds to 2 slots, and so on.drx-ShortCycle Value in ms. ms1 corresponds to 1 ms, ms2 corresponds to2 ms, and so on. drx-ShortCycleTimer Value in multiples ofdrx-ShortCycle. A value of 1 corresponds to drx- ShortCycle, a value of2 corresponds to 2 * drx-ShortCycle and so on. drx-SlotOffset Value in1/32 ms. Value 0 corresponds to 0 ms, value 1 corresponds to 1/32 ms,value 2 corresponds to 2/32 ms, and so on.

drx-onDurationTimer is the duration at the beginning of a DRX cycle.drx-SlotOffset is slot delay before starting drx-onDurationTimer.

drx-StartOffset is a subframe in which the DRX cycle is started.

drx-InactivityTimer is the duration after PDCCH occasion, indicatinginitial UL or DL user data transmission for a MAC entity.

drx-RetransmissionTimerDL (per DL HARQ process) is a maximum durationuntil DL retransmission is received.

drx-RetransmissionTimerUL (per UL HARQ process) is a maximum durationuntil a grant for UL retransmission is received.

drx-LongCycle is a long DRX cycle.

drx-ShortCycle (optional) is a short DRX cycle.

drx-ShortCycleTimer (optional) is a duration during which the UE shouldfollow the short DRX cycle.

drx-HARQ-RTT-TimerDL (per DL HARQ process) is a minimum duration beforeDL assignment for HARQ retransmission is expected by the MAC entity.

drx-HARQ-RTT-TimerUL (per UL HARQ process) is a minimum duration beforea UL HARQ retransmission grant is expected by the MAC entity.

A DRX command MAC CE or a long DRX command MAC CE is identified by a MACPDU lower header with a logical channel ID (LCD). A fixed size is 0bits.

Table 5 shows an example of an LCID value for a DL-SCH.

TABLE 22 Index LCID values 111011 Long DRX Command 111100 DRX Command

PDCCH monitoring activity of the UE is managed by DRX and BA.

When DRX is configured, the UE does not need to continuously monitor thePDCCH.

DRX has the following features:

-   -   on-duration: duration that the UE waits for, after waking up, to        receive the PDCCH. If the UE successfully decodes the PDCCH, the        UE stays awake and starts an inactivity timer;    -   inactivity-timer: duration in which the UE waits to successfully        decode the PDCCH from the last successful decoding of the PDCCH.        If the UE fails to decode the PDCCH, the UE may go back to        sleep. The UE should restart the inactivity timer following        single successful decoding of the PDCCH for first transmission        only (i.e., not for retransmission);    -   retransmission timer: duration until retransmission is expected;    -   cycle: specifies periodic repetition of an on-duration and a        period of inactivity.

Next, DRX described in the MAC layer will be described. The MAC entityused hereinafter may be represented as a UE or a MAC entity of the UE.

The MAC entity may be configured by RRC with DRX functionality thatcontrols PDCCH monitoring activity of the UE for a C-RNTI, a CS-RNTI, aTPC-PUCCH-RNTI, a TPC-PUSCH-RNTI, and a TPC-SRS-RNTI of the MAC entity.When using DRX operation, the MAC entity should monitor the PDCCH. Whenthe MAC entity is in RRC_CONNECTED, if DRX is configured, the MAC entitymay discontinuously monitor the PDCCH using the DRX operation;otherwise, the MAC entity should constantly monitor the PDCCH.

RRC controls the DRX operation by configuring parameters in Table 3 andTable 4 (DRX configuration information).

If the DRX cycle is configured, Active Time includes the time while:

-   -   drx-onDurationTimer or drx-InactivityTimer or        drx-RetransmissionTimerDL or drx-RetransmissionTimerUL or        ra-ContentionResolutionTimer is running; or    -   a scheduling request is sent on PUCCH and is pending; or    -   a PDCCH indicating new transmission addressed to the C-RNTI of        the MAC entity has not been received after successful reception        of an RAR for a random access preamble not selected by the MAC        entity among contention-based random access preambles.

If the DRX is configured, the MAC entity should perform operation asshown in Table 23 below.

TABLE 23 1>if a MAC PDU is transmitted in a configured uplink grant: 2>start the drx-HARQ-RTT-TimerUL for the corresponding HARQ process  immediately after the first repetition of the corresponding PUSCH  transmission;  2>stop the drx-RetransmissionTimerUL for thecorresponding HARQ process. 1>if a drx-HARQ-RTT-TimerDL expires:  2>ifthe data of the corresponding HARQ process was not successfully decoded:  3>start the drx-RetransmissionTimerDL for the corresponding HARQ   process. 1>if a drx-HARQ-RTT-TimerUL expires:  2>start thedrx-RetransmissionTimerUL for the corresponding HARQ process. 1>if a DRXCommand MAC CE or a Long DRX Command MAC CE is received:  2>stopdrx-onDurationTimer;  2>stop drx-InactivityTimer. 1>ifdrx-InactivityTimer expires or a DRX Command MAC CE is received:  2>ifthe Short DRX cycle is configured:   3>start or restartdrx-ShortCycleTimer;   3>use the Short DRX Cycle.  2>else:   3>use theLong DRX cycle. 1>if drx-ShortCycleTimer expires:  2>use the Long DRXcycle. 1>if a Long DRX Command MAC CE is received:  2>stopdrx-ShortCycleTimer:  2>use the Long DRX cycle. 1>if the Short DRX Cycleis used, and [(SFN × 10) + subframe number] modulo  (drx-ShortCycle) =(drx-StartOffset) modulo (drx-ShortCycle); or 1>if the Long DRX Cycle isused, and [(SFN × 10) + subframe number] modulo  (drx-LongCycle) =drx-StartOffset:  2>if drx-SlotOffset is configured:   3>startdrx-onDurationTimer after drx-SlotOffset.  2>else:   3>startdrx-onDurationTimer. 1>if the MAC entity is in Active Time:  2>monitorthe PDCCH;  2>if the PDCCH indicates a DL transmission or if a DLassignment has been   configured:   3>start the drx-HARQ-RTT-TimerDL forthe corresponding HARQ process    immediately after the correspondingPUCCH transmission;   3>stop the drx-RetransmissionTimerDL for thecorresponding HARQ    process.  2>if the PDCCH indicates a ULtransmission:   3>start the drx-HARQ-RTT-TimerUL for the correspondingHARQ process    immediately after the first repetition of thecorresponding PUSCH    transmission;   3>stop thedrx-RetransmissionTimerUL for the corresponding HARQ    process.  2>ifthe PDCCH indicates a new transmission (DL or UL):   3>start or restartdrx-InactivityTimer. 1>else (i.e. not part of the Active Time):  2>nottransmit type-0-triggered SRS. 1>if CQI masking (cqi-Mask) is setup byupper layers:  2>if drx-onDurationTimer is not running:   3>not reportCSI on PUCCH. 1>else:  2>if the MAC entity is not in Active Time:  3>not report CSI on PUCCH.

Regardless of whether the MAC entity is monitoring the PDCCH, the MACentity transmits HARQ feedback and a type 1 trigger SRS when suchsignals are expected.

The MAC entity does not need to monitor the PDCCH if the MAC entity isnot a complete PDCCH occasion (e.g., the active time starts or expiresin the middle of a PDCCH occasion).

Next, DRX for paging will be described.

The UE may use DRX in RRC_IDLE and RRC_INACTIVE states in order toreduce power consumption. The UE monitors one paging occasion (PO) perDRX cycle, and one PO may consist of multiple time slots (e.g.,subframes or OFDM symbols) in which paging DCI may be transmitted. In amulti-beam operation, the length of one PO is one cycle of beam sweepingand the UE may assume that the same paging message is repeated in allbeams of a sweeping pattern. The paging message is the same for both RANinitiated paging and CN initiated paging.

One paging frame (PF) is one radio frame that may include one ormultiple POs.

Upon receiving RAN paging, the UE initiates an RRC connection resumptionprocedure. Upon receiving CN initialized paging in RRC_INACTIVE state,the UE transitions to RRC_IDLE to notify a NAS.

Meanwhile, when UEs supporting V2X communication perform sidelinkcommunication, the UEs need to perform an automatic gain control (AGC)operation in the step of receiving information. The AGC operation isperformed first in signal processing needed for the function of enablingsignals to be kept at a constant amplitude level. In LTE V2X, AGCoperation may be performed using the first OFDM symbol from among 14OFDM symbols included in a single subframe. AGC operation is requiredfor both a control channel and a data channel, and a time required forAGC may vary depending on the modulation order. In the followingdescription, the time required for AGC will be referred to as “AGCtime”, the control channel for AGC will be referred to as PSCCH, and thedata channel for AGC will be referred to as PSCCH. For example, assumingthat the modulation order of a PSCCH uses QPSK and a PSSCH uses higherorder modulation (e.g., 16QAM), the AGC time of PSCCH and the AGC timeof PSSCH may be changed.

On the other hand, when the UE selects a resource pattern to betransmitted from among a plurality of resource pattern(s) having been(pre-)configured by a base station (BS), the UE may perform resourcesensing and then select one or more patterns (i.e., resources to betransmitted) according to the sensed result. As a result, the UE canprevent collision with transmission (Tx) resources of another UE. Thissensing and resource selection process may be performed by referring tolatency requirements, reliability requirements, and/or the presence orabsence of periodicity, each of which corresponds to Tx information tobe transmitted by the UE.

In the following embodiments, a method for transmitting and receivingsignals needed for high-precision UE positioning will be described withreference to the attached drawings. For high-precision positioning,synchronization between anchor nodes is of importance. Specifically,positioning performance of technology (e.g., OTDoA) for measuring a timedifference between two or more different anchor nodes (e.g., basestation (BS), eNB, road side unit (RSU), or gNB, etc.) sensitivelyreacts to a synchronization error between anchor nodes. In addition, amethod for measuring RTT (e.g., ToA) may not require synchronizationbetween anchor nodes, but should repeatedly communicate with severalanchor nodes to correctly measure the UE position. In the embodiment(s),as can be seen from FIG. 33, based on the environment in which the UEcan communicate with three or more base stations (BSs), the presentdisclosure proposes a variety of hybrid techniques (OTDoA, UTDoA,multicell RTT (ToA)-based hybrid techniques) through extension of amethod of measuring RTT of multiple cells, and also proposes a methodfor increasing the accuracy of UE positioning by forming a newelliptical curve. (In FIG. 3, ‘dx,y’ denotes the distance between X andY nodes. In addition, the present disclosure proposes a method forestimating a synchronization error value between anchor nodes.

In the following description, the anchor node will hereinafter bereferred to as a base station (BS) unless another assumption is made. Inthis case, the anchor node (BS) may be implemented as a base stationsuch as an eNB or gNB. In V2X communication, the anchor node (BS) mayalso refer to a road side unit (RSU) installed at a roadside.Alternatively, the anchor node may refer to a specific UE in which it isdetermined that the UE position is correct or it is assumed that the UEpositioning error is less than a predetermined threshold.

Embodiment(s)

First, the following description relates to a method for adjustingsynchronization between asynchronous UEs, and more particularly to amethod for measuring multicell RTT through RSTD reporting. Here, in thefollowing positioning process to be described, although the method foradjusting synchronization between the UEs can be performed with prioritywhen at least two BSs are not synchronized with each other, it should benoted that the above synchronous adjustment method can also be used forsynchronization needed for other uses irrespective of the positioningprocess.

Referring to FIG. 33, the second BS according to one embodiment mayreceive a second signal that is transmitted by the UE having received afirst signal from the first BS after lapse of a first interval (StepS3301), and may receive a fourth signal that is transmitted by the UEhaving received a third signal from the second BS after lapse of thefirst interval (Step S3302). In this case, a synchronization errorbetween the first BS and the second BS may be determined based on afirst time where the second BS receives the second signal and a secondtime where the second BS receives the fourth signal. Thereafter, thesecond BS may synchronize with the first BS based on the synchronizationerror.

The above description will hereinafter be given with reference to FIG.34. Referring to FIG. 34, the UE having received the first signal (e.g.,signals having A and D routes shown in FIG. 34) from the first BS maytransmit a second signal (e.g., signals having F and J routes shown inFIG. 34) to the second BS after the first interval

(t_(Rx − Tx)),

such that the second BS can receive the second signal from the UE. Thatis, the second BS can receive signals having A, D, F and J routes asshown in FIG. 4.

In addition, after lapse of the first interval, the second BS mayreceive a fourth signal (e.g., signals having G and K routes shown inFIG. 34) from the UE having received the third signal (e.g., signalshaving H, I and E routes shown in FIG. 34) from the second BS. That is,as can be seen from FIG. 34, the second BS can receive signals having H,I, E, G, and K routes. In this case, the synchronization error(alternatively, the synchronization error e(a,b) between the first BS(BS #1) and the second BS (BS #b)) between the first BS and the secondBS can be determined based on a time point

$\left( {t_{0} + t_{{Rx} - {Tx}} + \frac{d_{a,{UE}}}{c} + \frac{d_{b,{UE}}}{c}} \right)$

where the second BS receives the second signal and a time point

$\left( {t_{0} + {e\left( {a,b} \right)} + t_{{Rx} - {Tx}} + \frac{2d_{B,{UE}}}{c}} \right)$

where the second BS receives the fourth signal

In detail, the synchronization error can be determined from theproposition that each of the first interval (t_(Rx-Tx)), the distance(d_(a,UE)) between the UE and the first B S, the distance (d_(b,UE))between the UE and the second BS, a time difference (e.g., a timesection between J and K points in FIG. 34) between a time point wherethe second BS receives the second signal and a time point where thesecond BS receives the fourth signal is identical to a time difference(e.g., a time section RSTD(a,b) between D and E points in FIG. 34)between a time point where the UE receives the first signal and a timepoint where the UE receives the third signal. The above-mentionedproposition can be represented by the following equation 5.

$\begin{matrix}{{t_{0} + {e\left( {a,b} \right)} + t_{{Rx} - {Tx}} + \frac{d_{b,{UE}}}{c} + \frac{d_{a,{UE}}}{c}} = {t_{0} + \frac{2d_{a,{UE}}}{c} + {{RSTD}\left( {a,b} \right)} + {t_{{Rx} - {Tx}}.}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

The following equation 6 can be derived from Equation 5.

$\begin{matrix}{{e\left( {a,b} \right)} = {\frac{d_{a,{UE}}}{c} - \frac{d_{b,{UE}}}{c} + {{RSTD}\left( {a,b} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 5, t₀ denotes the same time point e(a,b) is thesynchronization error, t_(Rx-Tx) denotes the first interval, d_(a,UE)denotes the distance between the UE and the first BS, d_(b,UE) denotesthe distance between the UE and the second BS, and RSTD(a,b) denotes atime difference between the time point where the UE receives the firstsignal and the other time point where the UE receives the third signal.

Meanwhile, the first signal and the third signal may be transmitted atthe same time point (t₀) by the first BS and the second BS having asynchronization error.

In addition, the first interval (t_(Rx-Tx)), that indicates a differencebetween the time point where the first BS (BS #a) receives signals fromthe UE and the other time point where the UE transmits signals to thefirst BS (BS #a), may be received from the UE. That is, the UE mayreport the interval (t_(Rx-Tx)) to the reference BS or the serving BS.Here, the UE may also report the interval (t_(Rx-Tx)) to the pluralityof BSs as needed. If necessary, the reporting object of the UE may alsobe the first BS (BS #a) or the second BS (BS #b). In addition, each BSmay also share the above information (t_(Rx-Tx)) received from the UEwith other devices using a wired/wireless backhaul as needed

A time difference between the time point where the UE receives the firstsignal and the other point where the UE receives the third signal may bereceived from the UE. The UE may measure a difference (RSTD) in Rx timepoint between the Tx signal of the first BS (BS #a) and the Tx signal ofthe second BS (BS #b). In addition, the UE can transmit the RSTD to theBS or the location server through physical layer signaling or higherlayer signaling. In this case, the UL positioning signal can betransmitted based on a signal reception (Rx) time where the UE receivessignals from a reference BS of the RSTD (i.e., RSTD reference BS). Inthis case, the above reference BS may be selected by the UE itself, ormay also be designated by the BS. The signal delivered from the UE tothe first BS (BS #a) can also be received by the second BS (BS #b). Tothis end, UE signaling information (including the type of Tx signals tobe transmitted from UE, a transmission (Tx) time of the Tx signals to betransmitted from the UE, the type of resources to be used for the Txsignals) can be shared between the BSs through wired/wireless backhaul.

The RSTD reference BS may measure an RTT (or the distance (d_(a,UE))between the BS and the UE) between the UE and the BS using feedbackinformation (t_(Rx-Tx)). In detail, the distance (d_(a,UE)) between theUE and the first BS may be received from the first BS. Here, thedistance (d_(a,UE)) may be calculated based on the first interval(t_(Rx-Tx)) and the time section ranging from the time point where thefirst BS transmits the first signal to the other time point where thefirst BS receives the second signal. Namely, when the first BS (BS #a)measures

${t_{0} + t_{{Rx} - {Tx}} + \frac{2d_{a,{UE}}}{c}},$

t_(Rx-Tx) from the UE is fed back to the first BS (BS #a) as feedbackinformation, so that the first BS (BS #a) can measure

$\frac{2d_{a,{UE}}}{c}$

using the time information (t₀) that has already been transmitted by thefirst BS itself. Alternatively, the distance (d_(a,UE)) between the UEand the first BS may be measured and reported by the UE, and this UEmeasurement value may also be reported to the second BS.

Similarly, the distance (d_(b,UE)) between the UE and the second BS maybe calculated based on the first interval (t_(Rx-Tx)) and a timeduration from the Tx time of the third signal to the Rx time of thefourth signal after transmission of the third signal. Alternatively, thesecond BS (BS #b) may receive signals from the UE at a time point

$t_{0} + t_{{Rx} - {Tx}} + \frac{2d_{a,{UE}}}{c} + \frac{2d_{b,{UE}}}{c}$

(see ‘J’ depicted in FIG. 34). In this case, the second BS (BS #b) mayreceive the signals from the UE at a time point

$t_{0} + {e\left( {a,b} \right)} + \frac{2d_{b,{UE}}}{c} - {{RSTD}\left( {a,b} \right)} + {t_{{Rx} - {Tx}}.}$

At this time, the second BS (BS #b) may receive signals from the UE at atime point

$t_{0} + {e\left( {a,b} \right)} + \frac{2d_{b,{UE}}}{c} - {{RSTD}\left( {a,b} \right)} + {t_{{Rx} - {Tx}}.}$

Here, t₀+e(a,b) denotes a time point where the original signal hasalready been transmitted, and can be known to the second BS (BS #b). Inaddition, since RSTD(a,b) and t_(Rx-Tx) denote values fed back from theUE, RSTD(a,b) and t_(Rx-Tx) may be considered to be known values, sothat

$\frac{2d_{b,{UE}}}{c}$

can be measured. Namely, the first BS (BS #a) can measure

$\frac{d_{a,{UE}}}{c}$

through RTT. Likewise, the second BS (BS #b) can measure

$\frac{d_{b,{UE}}}{c}.$

In summary, information (t_(Rx-Tx)) about a difference between Rx and Txsignals of the RSTD and the specific BS can be fed back to the BS by theUE, so that each BS can calculate the RTT (indicating the distancebetween the BS and the UE) based on the feedback information. Inaddition, the synchronization error between the anchor nodes can bemeasured through the RTT measured by the BS and the RSTD report of theUE. If the synchronization error between the networks is measured asdescribed above, the BS can further improve OTDOA performance. Assumingthat the UE reports the RSTD to the BS and then uses OTDOA based on thereported RSTD, there is a possibility that the accuracy of positioningwill decrease due to occurrence of the synchronization error between theBSs. In order to address this issue, the present disclosure can measureand compensate for the synchronization error between the BSs, resultingin an increase in positioning accuracy.

The above-described method can reduce the positioning error throughjoint intersection together with the following A), B), C), and D)positioning methods, wherein: A) UE positioning is performed through ToAmeasurement (RTT measurement) between the BS and the UE; B) UEpositioning (OTDOA) is performed through TDoA measurement of the signaltransferred from the BS; C) UE positioning (UTDOA) is performed throughTDoA measurement of the signal transferred from the UE; and D) UEpositioning is performed using intersection points between one ellipsoidand the other ellipsoid after receiving the reception time of the signal(referred to as ‘BS-transmitted signal’) transmitted by the BS and thereception time of the signal (referred to as ‘UE-transmitted signal’)transmitted by the UE. Hereinafter, among the above-described methods A)to D), the method D) for performing UE positioning based on theintersection points between ellipsoids will hereinafter be described indetail. The following positioning method to be described is not alwayscombined with the above-mentioned synchronization errormeasurement/correction method, and it should be noted that the followingpositioning method can also be used as an independent positioning methodas necessary.

FIG. 35 shows an example of the positioning method based on theintersection points between the ellipsoids. Referring to FIG. 35, whenthe UE having received a fifth signal (e.g., signals having A and Broutes in FIG. 35) from the first BS transmits a sixth signal (e.g.,signals having C and D routes in FIG. 35) to the second BS after lapseof the second interval (t_(a,b)), an elliptical route may be formedbased on the reception time of the sixth signal (i.e., C-D route signalin FIG. 35) received by the second BS, so that the second BS can measurethe UE position based on the resultant elliptical route. That is, basedon time information signaled by the UE and the reception time of theUE-transmitted signal, the second BS (BS #b) may create the ellipticalroute in which the first BS (BS #a) and the second BS (BS #b) are set tofocal points (e.g., reference points).

In more detail, after lapse of a predetermined time from the receptiontime where the UE receives the signal from the first BS (BS #a), the UEtransmits the signal to the second BS (BS #b), resulting in formation ofthe elliptical route in which the first BS (BS #a) and the second BS (BS#b) are set to focal points.

The first BS (BS #a) may transmit a signal at the time point (t₀), andthe UE may then measure the reception time of the signal. After lapse ofa predetermined time (t_(a,b)), the UE may transmit the signal to thesecond BS (BS #b), and the second BS (BS #b) may then record thereceived signal. At this time, the UE may transmit, to the BS, a timedifference (t_(a,b)) between the time where the UE transmits the signalto the first BS (BS #a) and the other time where the UE transmits thesignal to the second BS (B S #b), through physical layer signaling orhigher layer signaling. At this time, the UE may also perform directsignaling to the second BS (BS #b). Alternatively, after the UE performssignaling to the first BS (BS #a), the first BS (BS #a) may then performsignaling to the second BS (BS #b) using a backhaul signal.

Assuming that the BSs are synchronized with each other, the second BS(BS #b) may calculate

$r_{a,b} = {\frac{d_{a,{UE}}}{c} + \frac{d_{b,{UE}}}{c}}$

by measuring

$t_{{rx},b} = {t_{0} + \frac{d_{a,{UE}}}{c} + t_{a,b} + {\frac{d_{b,{UE}}}{c}.}}$

At this time, it can be assumed that the synchronous BSs have alreadyrecognized the parameter (t₀) as a known value. Here, it can be assumedthat the parameter (t₀) has already been recognized by the BSs, and itcan also be assumed that the UE can perform signaling of t_(a,b),resulting in formation of ellipsoids in which the first BS (BS #a) andthe second BS (BS #b) are set to the focal points. If the aboveoperation is performed with three or more BSs, the UE position can bemeasured using the intersection point between the ellipsoids. As can beseen from FIG. 35, the UE position can be measured based on theintersection point between the ellipsoids where two BSs are set to thefocal points.

Hereinafter, the exemplary case in which the BSs are not synchronizedwith each other will be described in detail with reference to FIG. 36.

If the BSs are not synchronized with each other, a process forperforming synchronization between the BSs is needed. For example, thereis a need for the second BS to perform a specific operation that enablesthe second BS (BS #b) to receive the signal having been transmitted bythe first BS (BS #a) may be required for the second BS. When the firstBS transmits the signal to the UE at the time point (t₀), the second BS(BS #b) may propose an operation of receiving the signal from the firstBS (BS #a). This situation may be interpreted as overhearing the signalthat the first BS (BS #a) transmits to the UE. For this operation,information about resources (e.g., slot, subframe, frame, frequencyresource, RS sequence, etc.) required for signal transmission of thefirst BS (BS #a) can be shared between the BSs through a wired/wirelessbackhaul (or a physical layer signal or a higher layer signal). In FIG.36, ‘Case A’ may denote a case in which BS-to-BS over-the-air (OTA)signaling information and the signal that the first BS (BS #a) transmitsto the UE are simultaneously received, and “Case B” may denote anothercase in which the first BS (BS #a) transmits the signal to the second BS(BS #b) at a separate time. In this case, it is assumed that theoperation in which the first BS (BS #a) transmits the signal to the UEand the other operation in which the first BS (BS #a) transmits thesignal to the second BS (BS #b) are performed separately from eachother. In addition,

$\frac{d_{a,b}}{c}$

can be calculated using the relative distance (or location information)between the BSs. To this end, the UE should share its own locationinformation with the BSs. Accordingly, t₀ can be calculated at the timepoint

$t_{0} + \frac{d_{a,b}}{c}$

where the second BS (BS #b) receives the signal. As a result, althoughthe BSs are not synchronized with each other, direct over-the-air (OTA)signaling between the BSs is performed to recognize a time differencebetween the BSs (i.e., a BS-to-BS time difference), so that theabove-mentioned ellipsoid-based positioning method can be madeavailable.

In summary, location information of the BSs can be shared between theBSs using a BS-to-BS wired/wireless backhaul signal. In order to measurea time delay (latency) between the BSs, the BSs can share informationabout when a signal will be transmitted and information about whichsignal will be transmitted, and/or can share information about when asignal will be received and information about which signal will bereceived. In this case, the first BS (BS #a) and the second BS (BS #b)may share information about when a signal will be transmitted to the UEand information about which signal will be transmitted to the UE using awired/wireless backhaul. As a result, as soon as the first BS (BS #a)transmits signals, the second BS (BS #b) can receive signals. On theother hand, the BS-to-BS transmission (Tx) time point can also bemeasured using BS-to-BS over-the-air (OTA) signaling separately from theaforementioned method. Here, location information between the BSs(BS-to-BS location information) can be used on the assumption that aBS-to-BS channel is ‘LOS’, so that the transmission time point can beestimated using a propagation delay of the BSs.

Although the inventive aspects and/or embodiment(s) of the presentdisclosure can be regarded as one proposed method, it should be notedthat a combination thereof can also be considered to be a new method. Inaddition, it should also be understood that the inventive aspects arenot limited to the embodiments and also are not limited to a specificsystem and can be applied to other systems. In case of using all of theparameters and/or operations of the embodiment(s), a combination of theparameters and operations, information about whether or not thecorresponding parameter and/or operation is applied, and/or acombination of the parameters and/or operations, the BS maypre-configure information through higher layer signaling to the UEand/or physical layer signaling to the UE, or may define suchinformation in the system in advance. In addition, each aspect of theembodiment(s) may be defined as one operation mode, and one of theoperation modes may be pre-configured through higher layer signalingand/or physical layer signaling between the BS and the UE, so that theBS can operate in the corresponding operation mode. The transmissiontime interval (TTI) of the embodiment(s) or a resource unit for signaltransmission may correspond to various lengths of units, such as asub-slot/slot/subframe or a basic unit for signal transmission. The UEdescribed in the embodiment(s) may correspond to various types ofdevices such as a vehicle, a pedestrian UE, and the like. In addition,operations of the UE, BS, and/or RSU (road side unit) described in theembodiment(s) are not limited to a specific type of devices, and canalso be applied to different types of devices. For example, in theembodiment(s), the details written in base station (BS) operations canbe applied to UE operations. Alternatively, among the details of theembodiment(s), some content applicable to direct UE-to-UE communicationcan also be used to communication between the UE and the BS (e.g.,uplink or downlink communication). At this time, the proposed method canbe used for communication between the UE and the BS (or a relay node),communication between the UE and a specific type of UE such as a UE-typeRSU, and/or communication between specific types of wireless devices. Inthe above description, the term “base station BS” can also be replacedwith relay node, UE-type RSU, etc. as necessary.

The present disclosure is not limited to direct communication betweenUEs, but may also be used in uplink or downlink communication, and atthis time, a base station or a relay node can use the proposed method.

Since examples of the above-described various proposals may also beincluded as implementation methods of the present disclosure, it isobvious that they may be regarded as a kind of proposed methods.Further, although the foregoing proposals may be implementedindependently, some of the proposals may be combined (or integrated). Itmay be regulated that an eNB transmits information indicating whetherthe proposed methods are to be applied (or information indicating rulesof the proposed methods) to a UE by a predefined signal (e.g., aphysical-layer signal or a higher-layer signal).

Device Configuration According to Embodiment(s)

Hereinafter, a device to which the present disclosure is applicable willbe described.

FIG. 37 illustrates a wireless communication device according to anembodiment.

Referring to FIG. 37, the wireless communication system may include afirst device 9010 and a second device 9020.

The first device 9010 may be a BS, a network node, a Tx UE, an Rx UE, awireless device, a wireless communication device, a vehicle, a vehiclehaving an autonomous traveling function, a connected car, an unmannedaerial vehicle (UAV), an artificial intelligence (AI) module, a robot,an augmented reality (AR) device, a virtual reality (VR) device, a mixedreality (MR) device, a hologram device, a public safety device, an MTCdevice, an IoT device, a medical device, a FinTech device (or afinancial device), a security device, a weather/environment device, adevice related to a 5G service, or a device related to fourth industrialrevolution.

The second device 9020 may be a BS, a network node, a Tx UE, an Rx UE, awireless device, a wireless communication device, a vehicle, a vehiclehaving an autonomous traveling function, a connected car, a UAV, an AImodule, a robot, an AR device, a VR device, an MR device, a hologramdevice, a public safety device, an MTC device, an IoT device, a medicaldevice, a FinTech device (or a financial device), a security device, aweather/environment device, a device related to a 5G service, or adevice related to fourth industrial revolution.

The UE may include, for example, a cellular phone, a smartphone, alaptop computer, a digital broadcast terminal, a personal digitalassistant (PDA), a portable multimedia player (PMP), a navigationsystem, a slate PC, a tablet PC, an ultrabook, a wearable device (e.g.,a smartwatch, smartglasses, or a head mounted display (HMD)), and thelike. The HMD may be, for example, a type of display device that is wornon the head. For example, the HMD may be used to implement VR, AR, orMR.

The UAV may be, for example, an aircraft without a human being onboard,which aviates by a wireless control signal. The VR device may include,for example, a device for implementing an object or a background of thevirtual world. The AR device may include, for example, a deviceimplemented by connecting an object or a background of the virtual worldto an object or a background of the real world. The MR device mayinclude, for example, a device implemented by merging an object or abackground of the virtual world into an object or a background of thereal world. The hologram device may include, for example, a device thatimplements a stereoscopic image of 360 degrees by recording andreproducing stereoscopic information, using an interference phenomenonof light that is generated by two laser beams meeting each other whichis called holography. The public safety device may include, for example,an image relay device or an image device that is wearable on the body ofa user. The MTC device and the IoT device may be, for example, devicesthat do not require direct human intervention or manipulation. Forexample, the MTC device and the IoT device may include smartmeters,vending machines, thermometers, smartbulbs, door locks, or varioussensors. The medical device may be, for example, a device used for thepurpose of diagnosing, treating, relieving, curing, or preventingdisease. For example, the medical device may be a device used for thepurpose of diagnosing, treating, relieving, or correcting injury orimpairment. For example, the medical device may be a device used for thepurpose of inspecting, replacing, or modifying a structure or afunction. For example, the medical device may be a device used tocontrol pregnancy. For example, the medical device may include a devicefor treatment, a device for operation, a device for (in vitro)diagnosis, a hearing aid, or an operation device. The security devicemay be, for example, a device installed to prevent a danger that mayarise and to maintain safety. For example, the security device may be acamera, a CCTV, a recorder, or a black box. The FinTech device may be,for example, a device capable of providing a financial service such asmobile payment. For example, the FinTech device may include a paymentdevice or a point of sale (POS) system. The weather/environment devicemay include, for example, a device for monitoring or predicting aweather/environment.

The first device 9010 may include at least one processor, such as aprocessor 9011, at least one memory, such as a memory 9012, and at leastone transceiver, such as a transceiver 9013. The processor 9011 mayperform the functions, procedures, and/or methods described above. Theprocessor 9011 may perform one or more protocols. For example, theprocessor 9011 may implement one or more layers of a radio interfaceprotocol. The memory 9012 may be connected to the processor 9011 andstore various types of information and/or commands. The transceiver 9013may be connected to the processor 9011 and controlled totransmit/receive a radio signal. The transceiver 9013 may be connectedto one or more antennas 9014-1 to 9014-n. The transceiver 9013 may beconfigured to transmit and receive the user data, control information,and radio signals/channels, mentioned in the methods and/or operationflowcharts of the present specification, through the one or moreantennas 9014-1 to 9014-n. In the present specification, the n antennasmay be n physical antennas or n logical antenna ports.

The second device 9020 may include at least one processor such as aprocessor 9021, at least one memory such as a memory 9022, and at leastone transceiver such as a transceiver 9023. The processor 9021 mayperform the functions, procedures, and/or methods described above. Theprocessor 9021 may implement one or more protocols. For example, theprocessor 9021 may implement one or more layers of the radio interfaceprotocol. The memory 9022 may be connected to the processor 9021 andstore various types of information and/or commands. The transceiver 9023may be connected to the processor 9021 and controlled totransmit/receive a radio signal. The transceiver 9023 may be connectedto one or more antennas 9024-1 to 9024-n. The transceiver 9023 may beconfigured to transmit and receive the user data, control information,and radio signals/channels, mentioned in the methods and/or operationflowcharts of the present specification, through the one or moreantennas 9024-1 to 9024-n.

The memory 9012 and/or the memory 9022 may each be connected inside oroutside the processor 9011 and/or the processor 9021 and connected toother processors by various techniques such as wired or wirelessconnection. FIG. 38 illustrates a wireless communication deviceaccording to an embodiment.

FIG. 38 is a detailed diagram of the first device 9010 or the seconddevice 9020 of FIG. 37. However, the wireless communication device ofFIG. 38 is not limited to the UE. The wireless communication device maybe an arbitrary suitable mobile computer device configured to implementone or more of a vehicle communication system or device, a wearabledevice, a portable computer, and a smartphone.

Referring to FIG. 38, the UE may include at least one processor (e.g., aDSP or a microprocessor) such as a processor 9110, a transceiver 9135, apower management module 9105, an antenna 9140, a battery 9155, a display9115, a keypad 9120, a global positioning system (GPS) chip 9160, asensor 9165, a memory 9130, an (optional) subscriber identificationmodule (SIM) card 9125, a speaker 9145, and a microphone 9150. The UEmay include one or more antennas.

The processor 9110 may be configured to perform the functions,procedures, and/or methods described above. According to animplementation example, the processor 9110 may implement one or moreprotocols such as layers of the radio interface protocol.

The memory 9130 may be connected to the processor 9110 to storeinformation related to operation of the processor 9110. The memory 9130may be located insider or outside the processor 9110 and may beconnected to other processors by various techniques such as wired orwireless connection.

A user may input various types of information (e.g., instructioninformation such as telephone numbers) by various techniques such aspressing a button on the keypad 9120 or activating voice using themicrophone 9150. The processor 9110 performs appropriate functions suchas receiving and/or processing information of the user and dialing atelephone number. For example, data (e.g., operational data) may beretrieved from the SIM card 9125 or the memory 9130 to perform theappropriate functions. As another example, the processor 10 may receiveand process GPS information from the GPS chip 9160 to perform functionsrelated to the location of the UE such as vehicle navigation, mapservices, or the like. As another example, the processor 9110 maydisplay various types of information on the display 9115 for referenceand convenience of the user.

The transceiver 9135 is connected to the processor 9110 to transmitand/or receive radio signals, such as RF signals. The processor 9110 maycontrol the transceiver 9135 to initiate communication and transmitradio signals including various types of information or data, such asvoice communication data. The transceiver 9135 may include one receiverand one transmitter for receiving and transmitting radio signals. Theantenna 9140 facilitates transmission and reception of radio signals. Insome implementations, upon receipt of radio signals, the transceiver9135 may forward and convert the signals to a baseband frequency forprocessing by the processor 9110. The processed signals may be processedaccording to various techniques, such as being converted into audibleinformation so that the signals may be output through the speaker 9145or into readable information.

In some implementations, the sensor 9165 may be connected to theprocessor 9110. The sensor 9165 may include one or more sensing devicesconfigured to detect various types of information, including, withoutbeing limited to, velocity, acceleration, light, vibration, proximity,position, and images. The processor 9110 receives and processes thesensor information obtained from the sensor 9165 and performs variousfunctions such as collision avoidance and autonomous driving.

In the example of FIG. 38, various components (e.g., a camera and a USBport) may be further included in the UE. For example, the camera may beconnected to the processor 9110, which may be used for a variety ofservices such as autonomous driving and vehicle safety services.

In this way, FIG. 38 is purely exemplary and implementation is notlimited thereto. For example, some components (e.g., the keypad 9120,the GPS chip 9160, the sensor 9165, the speaker 9145, and/or themicrophone 9150) may be excluded in some implementations.

FIG. 39 illustrates a transceiver of a wireless communication deviceaccording to an embodiment. For example, FIG. 39 may illustrate anexample of a transceiver that may be implemented in a frequency divisionduplex (FDD) system.

On a transmission path, at least one processor, such as the processordescribed with reference to FIGS. 34 and 35, may process data to betransmitted and transmit a signal such as an analog output signal to atransmitter 9210.

In the above example, in the transmitter 9210, the analog output signalmay be filtered by a low-pass filter (LPF) 9211 in order to eliminatenoise caused by, for example, previous digital-to-analog conversion(ADC), up-converted into an RF signal from a baseband signal by anup-converter (e.g., a mixer) 9212, and then amplified by an amplifiersuch as a variable gain amplifier (VGA) 9213. The amplified signal maybe filtered by a filter 9214, amplified by a power amplifier (PA) 9215,routed by a duplexer 9250/antenna switches 9260, and then transmittedthrough an antenna 9270.

On a reception path, the antenna 9270 may receive a signal in a wirelessenvironment. The received signal may be routed by the antenna switches9260/duplexer 9250 and then transmitted to a receiver 9220.

In the above example, in the receiver 9220, the received signal may beamplified by an amplifier such as a low-noise amplifier (LNA) 9223,filtered by a band-pass filter (BPF) 9224, and then down-converted intothe baseband signal from the RF signal by a down-converter (e.g., amixer) 9225.

The down-converted signal may be filtered by an LPF 9226 and amplifiedby an amplifier such as a VGA 9227 in order to obtain an analog inputsignal. The analog input signal may be provided to one or moreprocessors.

Furthermore, a local oscillator (LO) 9240 may generate an LO signal fortransmission and reception and transmit the LO signal to theup-converter 9212 and the down-converter 9224.

In some implementations, a phase-locked loop (PLL) 9230 may receivecontrol information from the processor and transmit control signals tothe LO 9240 so that the LO 9240 may generate LO signals for transmissionand reception at an appropriate frequency.

Implementations are not limited to a specific arrangement illustrated inFIG. 39 and various components and circuits may be arranged differentlyfrom the example illustrated in FIG. 39.

FIG. 40 illustrates a transceiver of a wireless communication deviceaccording to an embodiment. For example, FIG. 40 may illustrate anexample of a transceiver that may be implemented in a time divisionduplex (TDD) system.

In some implementations, a transmitter 9310 and a receiver 9320 of thetransceiver of the TDD system may have one or more features similar tothe transmitter and receiver of the transceiver of the FDD system.Hereinafter, the structure of the transceiver of the TDD system will bedescribed.

On a transmission path, a signal amplified by a PA 9315 of thetransmitter may be routed through a band select switch 9350, a BPF 9360,and antenna switch(s) 9370 and then transmitted through an antenna 9380.

On a reception path, the antenna 9380 receives a signal in a wirelessenvironment. The received signal may be routed through the antennaswitch(s) 9370, the BPF 9360, and the band select switch 9350 and thenprovided to the receiver 9320.

FIG. 41 illustrates an operation of a wireless device related tosidelink communication, according to an embodiment. The operation of thewireless device related to sidelink described in FIG. 41 is purelyexemplary and sidelink operations using various techniques may beperformed by the wireless device. Sidelink may be a UE-to-UE interfacefor sidelink communication and/or sidelink discovery. Sidelink maycorrespond to a PC5 interface. In a broad sense, a sidelink operationmay be transmission and reception of information between UEs. Sidelinkmay carry various types of information.

Referring to FIG. 41, in step S9410, the wireless device may acquireinformation related to sidelink. The information related to sidelink maybe one or more resource configurations. The information related tosidelink may be obtained from other wireless devices or network nodes.

After acquiring the information related to sidelink, the wireless devicemay decode the information related to the sidelink in step S9420.

After decoding the information related to the sidelink, the wirelessdevice may perform one or more sidelink operations based on theinformation related to the sidelink in step S9430. The sidelinkoperation(s) performed by the wireless device may include the one ormore operations described in the present specification.

FIG. 42 illustrates an operation of a network node related to sidelinkaccording to an embodiment. The operation of the network node related tosidelink described in FIG. 42 is purely exemplary and sidelinkoperations using various techniques may be performed by the networknode.

Referring to FIG. 42, in step S9510, the network node may receiveinformation about sidelink from a wireless device. For example, theinformation about sidelink may be sidelink UE information used to informthe network node of sidelink information.

After receiving the information, in step S9520, the network node maydetermine whether to transmit one or more commands related to sidelinkbased on the received information.

According to the determination of the network node to transmit thecommand(s), the network node may transmit the command(s) related tosidelink to the wireless device in step S9530. In some implementations,after receiving the command(s) transmitted by the network node, thewireless device may perform one or more sidelink operations based on thereceived command(s).

FIG. 43 illustrates implementation of a wireless device and a networknode according to one embodiment. The network node may be replaced witha wireless device or a UE.

Referring to FIG. 43, a wireless device 9610 may include a communicationinterface 9611 to communicate with one or more other wireless devices,network nodes, and/or other elements in a network. The communicationinterface 9611 may include one or more transmitters, one or morereceivers, and/or one or more communication interfaces. The wirelessdevice 9610 may include a processing circuit 9612. The processingcircuit 9612 may include one or more processors such as a processor9613, and one or more memories such as a memory 9614.

The processing circuit 9612 may be configured to control the arbitrarymethods and/or processes described in the present specification and/orto allow, for example, the wireless device 9610 to perform such methodsand/or processes. The processor 9613 may correspond to one or moreprocessors for performing the wireless device functions described in thepresent specification. The wireless device 9610 may include the memory9614 configured to store data, program software code, and/or otherinformation described in the present specification.

In some implementations, the memory 9614 may be configured to storesoftware code 9615 including instructions for causing the processor 9613to perform a part or all of the above-described processes according tothe present disclosure when one or more processors, such as theprocessor 9613, are executed.

For example, one or more processors, such as the processor 9613, thatcontrol one or more transceivers, such as a transceiver 2223, fortransmitting and receiving information may perform one or more processesrelated to transmission and reception of information.

A network node 9620 may include a communication interface 9621 tocommunicate with one or more other network nodes, wireless devices,and/or other elements on a network. Here, the communication interface9621 may include one or more transmitters, one or more receivers, and/orone or more communication interfaces. The network node 9620 may includea processing circuit 9622. Here, the processing circuit 9622 may includea processor 9623 and a memory 9624.

In some implementations, the memory 9624 may be configured to storesoftware code 9625 including instructions for causing the processor 9623to perform a part or all of the above-described processes according tothe present disclosure when one or more processors, such as theprocessor 9623, are executed.

For example, one or more processors, such as processor 9623, thatcontrol one or more transceivers, such as a transceiver 2213, fortransmitting and receiving information may perform one or more processesrelated to transmission and reception of information.

The aforementioned implementations are achieved by combinations ofstructural elements and features in various manners. Each of thestructural elements or features may be considered selective unlessspecified otherwise. Each of the structural elements or features may becarried out without being combined with other structural elements orfeatures. In addition, some structural elements and/or features may becombined with one another to constitute implementations. Operationorders described in implementations may be rearranged. Some structuralelements or features of one implementation may be included in anotherembodiment or may be replaced with corresponding structural elements orfeatures of another implementation.

The implementations of the present disclosure may be embodied throughvarious techniques, for example, hardware, firmware, software, orcombinations thereof. In a hardware configuration, a method according tothe implementations may be embodied as one or more application specificintegrated circuits (ASICs), one or more digital signal processors(DSPs), one or more digital signal processing devices (DSPDs), one ormore programmable logic devices (PLDs), one or more field programmablegate arrays (FPGAs), one or more processors, one or more controllers,one or more microcontrollers, one or more microprocessors, etc.

In a firmware or software configuration, the implementations may beembodied as a module, a procedure, or a function. Software code may bestored in a memory and executed by a processor. The memory is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor by various methods.

It is apparent that ordinary persons skilled in the art may performvarious modifications and variations that can be made in the presentdisclosure without departing from the spirit or scope of the disclosure.While the present disclosure has been described with reference to anexample applied to a 3GPP LTE/LTE-A system or a 5G system (or NRsystem), the present disclosure is applicable to various other wirelesscommunication systems.

INDUSTRIAL APPLICABILITY

The embodiments described above may be applied to various mobilecommunication systems.

1. A method for receiving signals by a second base station (BS) in awireless communication system comprising: receiving, by the second basestation (BS), a second signal transmitted after lapse of a firstinterval by a user equipment (UE) having received a first signal from afirst base station (BS); and receiving, by the second base station (BS),a fourth signal transmitted after lapse of the first interval by theuser equipment (UE) having received a third signal from a second basestation (BS), wherein a synchronization error between the first basestation (BS) and the second base station (BS) is determined based on atime point where the second base station (BS) receives the second signaland a time point where the second base station (BS) receives the fourthsignal.
 2. The method according to claim 1, wherein: the second basestation (BS) is synchronized with the first base station (BS) based onthe synchronization error.
 3. The method according to claim 2, wherein:the second base station (BS) is configured to measure a position of theuser equipment (UE) based on an elliptical shape derived from areception time of a sixth signal transmitted after lapse of a secondinterval by the user equipment (UE) having received a fifth signal fromthe first base station (BS).
 4. The method according to claim 1,wherein: the first signal and the third signal are transmitted at thesame time by the first base station (BS) and the second base station(BS) having the synchronization error.
 5. The method according to claim1, wherein: the synchronization error is determined from a propositionthat each of the first interval, a distance between the user equipment(UE) and the first base station (BS), a distance between the UE and thesecond base station (BS), a time difference between a time point wherethe second base station (BS) receives the second signal and a time pointwhere the second base station (BS) receives the fourth signal isidentical to a time difference between a time point where the userequipment (UE) receives the first signal and a time point where the userequipment (UE) receives the third signal.
 6. The method according toclaim 1, wherein: a distance between the user equipment (UE) and thesecond base station (BS) is calculated based on the first interval and atime duration from a transmission time of the third signal to areception time of the fourth signal after transmission of the thirdsignal.
 7. The method according to claim 1, wherein: a distance betweenthe user equipment (UE) and the first base station (BS) is received fromthe first base station (BS).
 8. The method according to claim 7,wherein: a distance between the user equipment (UE) and the first basestation (BS) is calculated based on the first interval and a timeduration from a transmission time point where the first base station(BS) transmits the first signal to a reception time point where thefirst base station (BS) receives the second signal.
 9. The methodaccording to claim 1, wherein: the first interval is received from theuser equipment (UE).
 10. The method according to claim 1, wherein: atime difference between a time point where the user equipment (UE)receives the first signal and a time point where the user equipment (UE)receives the third signal is received from the user equipment (UE). 11.The method according to claim 1, wherein: the proposition is representedby a following equation: $\begin{matrix}{{t_{0} + {e\left( {a,b} \right)} + t_{{Rx} - {Tx}} + \frac{d_{b,{UE}}}{c} + \frac{d_{a,{UE}}}{c}} = {t_{0} + \frac{2d_{a,{UE}}}{c} + {{RSTD}\left( {a,b} \right)} + t_{{Rx} - {Tx}}}} & \lbrack{Equation}\rbrack\end{matrix}$ where, t₀ denotes the same time point, e(a,b) denotes thesynchronization error, t_(Rx-Tx) denotes the first interval, d_(a,UE)denotes the distance between the UE and the first BS, denotes thedistance between the UE and the second BS, and RSTD(a,b) denotes a timedifference between a time point where the user equipment (UE) receivesthe first signal and a time point where the user equipment (UE) receivesthe third signal.
 12. A second base station for use in a wirelesscommunication system comprising: a memory; and a plurality of processorscoupled to the memory, wherein at least one processor from among theplurality of processors is configured to: receive a second signaltransmitted after lapse of a first interval by a user equipment (UE)having received a first signal from a first base station (BS), andreceive a fourth signal transmitted after lapse of the first interval bythe user equipment (UE) having received a third signal from a secondbase station (BS), wherein a synchronization error between the firstbase station (BS) and the second base station (BS) is determined basedon a time point where the second base station (BS) receives the secondsignal and a time point where the second base station (BS) receives thefourth signal.
 13. The second base station according to claim 12,wherein: the user equipment (UE) is an autonomous driving vehicle or isembedded in the autonomous driving vehicle.